Contact has some relatively novel ideas especially as applied to ArmA 3, as well as a decent amount of new content - I like most of what's here, but the way BI handles DLC makes it difficult to recommend for anything but its SP campaign, pissing around in the editor, or MP with small groups of friends who all own it. If I could give a "Mixed" rating I couldn't think of a DLC or game more deserving. Since I can't, I'm going to lean towards a no - unless it's on sale and/or you're made of money, and you really like single-player ArmA.

Content:
+ New first-party terrain. Livonia's pretty nice, with a good number of new buildings, and ones updated from earlier in the series - most of which you can use on other terrains regardless of whether you own the DLC. Performs better than Tanoa. Apparently has a new lighting system, though I'm playing on settings that make it hard to notice the difference - still, it looks good and has plenty of interesting areas for mission-makers to use.

+ First-party shotguns, that are about as powerful but as limited as you'd hope for them to be. Even cooler that one of them is an under-barrel. That said, no tube-fed/pump-actions which have always been weird when they've shown up in the series, modded or otherwise. Probably due to engine limitations.

+ The LDF's Promet rifles - Great sci-fi-esque design, and well up to the standard of the rest of the base game's content.

~ The LDF and Spetznas are fairly well-developed, but make heavy use of reskinned vanilla and content from other DLC (In which case, if I'm not mistaken, you only need to own Contact to use them). They're a decent extension of A3's 20-minutes-into-the-future setting, but still leave quite a bit to be desired.
There's also a decent amount of civilian and guerrilla gear added.

- Weapons, equipment and vehicles are practically unusable for players where large communities (who don't mandate ownership of DLCs) are concerned. As cool as much of the content is, in this context it might as well not exist unless everyone within a given community owns it, or that community is willing to exclude their players who lack it. This goes double for the terrain.

Campaign:
+ Introduces the EMSPEC device mechanic. It's nothing revolutionary but it's an interesting way of having the player discover points of interest and manipulate enemy forces. That said there are many instances where enemy units will refuse the forged orders you send them - particularly where it'd be most useful.

+ More free-roaming missions, lots of little scenes and story-building things for you to find.

+ A3jank considered, pretty good presentation and atmosphere.

+ Includes content (particularly weapons) from other DLCs, and allows you to use them in the campaign regardless of whether you own the parent DLC. Not sure if the nag-screen overlay shows up, if it does it is what it is. Still better than not being able to use it what-so-ever.

~ Fairly well-written story, but character dialogue (Particularly the player-character) often breaks suspension of disbelief - At least the voice acting's improved.

~ A lot of walking from A-B - you can use the handful of vehicles to traverse the terrain, but at least for me it was way too risky. I don't mind this personally, just wish there were more going on between POIs.

~ Performance is poor (Disclaimer: My performance is almost always objectively poor; the following is going by my standard). The free-roam missions especially have quite a lot going on, and while as far as I can tell most stuff isn't spawned in until you've moved into their general vicinity, and are cleaned up as you move further away, my FPS has been low throughout and made it a bit of a slog - the biggest gripe being inconsistency. I'm fine with 12fps if it stays that way, but when it's bouncing between that and 40 it's even more frustrating.
Poor framerates seem to adversely affect the timing of some scripted and dialogue sequences.
All that said, if you get decent performance in larger-scale MP scenarios you'll probably be fine.

- Many instances of "What am I meant to do now?". The direction given to you by the game/its characters ranges from lacking to misleading.

- Most missions require the use of the mini-UGV. If you're carrying it, anything inside when it's acting as a backpack is lost when you deploy it. Not ideal if on foot.

- Arbitrary restrictions on stealing uniforms. For whatever reason, you can't take the Spetznas' Granit uniforms or looters' clothes, even though you can take LDF uniforms.

- Has you going solo for the vast majority - while ArmA's AI can be frustrating and dumb, this doesn't play to the game's strengths. Flashpoint's Gastovski missions did stealth gameplay better despite their inclusion of AI teammates.

- The free-roam missions are slightly too restrictive geographically - I want to move a couple hundred meters further west to dodge this area I know is being patrolled by too many enemies to take on, but my character takes that as his cue to pack up and go home.

- Frustrating use of "Danger Zones" - Areas in which you're not allowed to savescum, regardless of difficulty settings. Even on the easiest possible settings, ArmA 3's a pretty tough game and that's only exacerbated by the fact you're often on your own in these missions. This can lead to retrying the same objective within a mission several times over, having to execute each step in your plan perfectly, any ♥♥♥♥♥♥♥ reverting you back to that autosave.

- Some sub-objectives can't be completed if you complete the main objective, and their place within that structure is pretty weird. Eg (Very minor) disabling the UGV in Mission 4, "Ballistic Therapy". Regarding that same example, it also doesn't come up until you're close to that objective's main task, which in my case meant doubling back.

- ArmA 3 being ArmA 3. Continuing from the above example, the UGV got stuck(? Or that's just where it decided to stay) in defilade from the enemy infantry close by. I completed the hack, but it didn't do anything since it couldn't see or detect those enemies despite being within 20m. My player character says "Well that was effective" but lacking the sarcasm that would've been appropriate in this case lmao

- Speaking of which, the game forces you into a trap which, were it not a scripted sequence, the player would easily avoid. You can dump half a mag into the guy who locks you in the room before he "hides", ie disappears.

- Maybe it's just me being dumb, but I had a lot of trouble figuring out what I actually need to do with the EMSPEC device at certain points, particularly mission 4's main objective.

If you've read the DLC's description, this isn't a spoiler
Aliens:
They're much more Arrival crossed with Roadside Picnic than Independence Day or Battle: Los Angeles - which is cool, but given what ArmA 3 is, this is the most disappointing aspect of the DLC to me at least. When I first heard BI were making a DLC about aliens, what immediately came to mind was reliving the glory days of OFP (ArmA: Cold War Assault) addons, fighting massive alien invasion forces comprised of little green dudes with plasma guns, huge insect-like UFOs, Terminators and SST's Arachnids thrown in at the same time - just with more cohesive design & direction.
Then my cynical nature got the better of me, and turned out to be right:
The aliens we do get are little more than static models that move around, and launch attacks from other static models floating around them. No infantry, no explicit ground or air vehicles - outside of the campaign they're extremely boring, within the campaign they're used fairly effectively for what they are.

Contact has some relatively novel ideas especially as applied to ArmA 3, as well as a decent amount of new content - I like most of what's here, but the way BI handles DLC makes it difficult to recommend for anything but its SP campaign, pissing around in the editor, or MP with small groups of friends who all own it. If I could give a "Mixed" rating I couldn't think of a DLC or game more deserving. Since I can't, I'm going to lean towards a no - unless it's on sale and/or you're made of money, and you really like single-player ArmA. [u]Content:[/u] + New first-party terrain. Livonia's pretty nice, with a good number of new buildings, and ones updated from earlier in the series - most of which you can use on other terrains regardless of whether you own the DLC. Performs better than Tanoa. Apparently has a new lighting system, though I'm playing on settings that make it hard to notice the difference - still, it looks good and has plenty of interesting areas for mission-makers to use. + First-party shotguns, that are about as powerful but as limited as you'd hope for them to be. Even cooler that one of them is an under-barrel. That said, no tube-fed/pump-actions which have always been weird when they've shown up in the series, modded or otherwise. Probably due to engine limitations. + The LDF's Promet rifles - Great sci-fi-esque design, and well up to the standard of the rest of the base game's content. ~ The LDF and Spetznas are fairly well-developed, but make heavy use of reskinned vanilla and content from other DLC (In which case, if I'm not mistaken, you only need to own Contact to use them). They're a decent extension of A3's 20-minutes-into-the-future setting, but still leave quite a bit to be desired. There's also a decent amount of civilian and guerrilla gear added. - Weapons, equipment and vehicles are practically unusable for players where large communities (who don't mandate ownership of DLCs) are concerned. As cool as much of the content is, in this context it might as well not exist unless everyone within a given community owns it, or that community is willing to exclude their players who lack it. This goes double for the terrain. [u]Campaign:[/u] + Introduces the EMSPEC device mechanic. It's nothing revolutionary but it's an interesting way of having the player discover points of interest and manipulate enemy forces. That said there are many instances where enemy units will refuse the forged orders you send them - particularly where it'd be most useful. + More free-roaming missions, lots of little scenes and story-building things for you to find. + A3jank considered, pretty good presentation and atmosphere. + Includes content (particularly weapons) from other DLCs, and allows you to use them in the campaign regardless of whether you own the parent DLC. Not sure if the nag-screen overlay shows up, if it does it is what it is. Still better than not being able to use it what-so-ever. ~ Fairly well-written story, but character dialogue (Particularly the player-character) often breaks suspension of disbelief - At least the voice acting's improved. ~ A lot of walking from A-B - you can use the handful of vehicles to traverse the terrain, but at least for me it was way too risky. I don't mind this personally, just wish there were more going on between POIs. ~ Performance is poor (Disclaimer: My performance is almost always objectively poor; the following is going by my standard). The free-roam missions especially have quite a lot going on, and while as far as I can tell most stuff isn't spawned in until you've moved into their general vicinity, and are cleaned up as you move further away, my FPS has been low throughout and made it a bit of a slog - the biggest gripe being inconsistency. I'm fine with 12fps if it stays that way, but when it's bouncing between that and 40 it's even more frustrating. Poor framerates seem to adversely affect the timing of some scripted and dialogue sequences. All that said, if you get decent performance in larger-scale MP scenarios you'll probably be fine. - Many instances of "What am I meant to do now?". The direction given to you by the game/its characters ranges from lacking to misleading. - Most missions require the use of the mini-UGV. If you're carrying it, anything inside when it's acting as a backpack is lost when you deploy it. Not ideal if on foot. - Arbitrary restrictions on stealing uniforms. For whatever reason, you can't take the Spetznas' Granit uniforms or looters' clothes, even though you can take LDF uniforms. - Has you going solo for the vast majority - while ArmA's AI can be frustrating and dumb, this doesn't play to the game's strengths. Flashpoint's Gastovski missions did stealth gameplay better despite their inclusion of AI teammates. - The free-roam missions are slightly too restrictive geographically - I want to move a couple hundred meters further west to dodge this area I know is being patrolled by too many enemies to take on, but my character takes that as his cue to pack up and go home. - Frustrating use of "Danger Zones" - Areas in which you're not allowed to savescum, regardless of difficulty settings. Even on the easiest possible settings, ArmA 3's a pretty tough game and that's only exacerbated by the fact you're often on your own in these missions. This can lead to retrying the same objective within a mission several times over, having to execute each step in your plan perfectly, any fuckups reverting you back to that autosave. - Some sub-objectives can't be completed if you complete the main objective, and their place within that structure is pretty weird. Eg (Very minor) [spoiler]disabling the UGV in Mission 4, "Ballistic Therapy".[/spoiler] Regarding that same example, it also doesn't come up until you're close to that objective's main task, which in my case meant doubling back. - ArmA 3 being ArmA 3. Continuing from the above example, [spoiler]the UGV got stuck(? Or that's just where it decided to stay) in defilade from the enemy infantry close by. I completed the hack, but it didn't do anything since it couldn't see or detect those enemies despite being within 20m. My player character says "Well that was effective" but lacking the sarcasm that would've been appropriate in this case lmao - Speaking of which, the game forces you into a trap which, were it not a scripted sequence, the player would easily avoid. You can dump half a mag into the guy who locks you in the room before he "hides", ie disappears. - Maybe it's just me being dumb, but I had a lot of trouble figuring out what I actually need to do with the EMSPEC device at certain points, particularly mission 4's main objective. [/spoiler] If you've read the DLC's description, this isn't a spoiler [spoiler][u]Aliens:[/u] They're much more Arrival crossed with Roadside Picnic than Independence Day or Battle: Los Angeles - which is cool, but given what ArmA 3 is, this is the most disappointing aspect of the DLC to me at least. When I first heard BI were making a DLC about aliens, what immediately came to mind was reliving the glory days of OFP (ArmA: Cold War Assault) addons, fighting massive alien invasion forces comprised of little green dudes with plasma guns, huge insect-like UFOs, Terminators and SST's Arachnids thrown in at the same time - just with more cohesive design & direction. Then my cynical nature got the better of me, and turned out to be right: The aliens we do get are little more than static models that move around, and launch attacks from other static models floating around them. No infantry, no explicit ground or air vehicles - outside of the campaign they're extremely boring, within the campaign they're used fairly effectively for what they are. [/spoiler]