You probably already know this guy, he was in the tutorial, but this is what you need to know for multiplayer.

Hes very good against pretty much all classes, hes the only one who can block currently and has very high damage skills. Hes great for PvP but not as good against the current Bots, since they tend to only spam skills, whirlwind spam will wreck you much easier than other classes that can avoid it.
Be very careful with your quick attacks, they're broad swings and can easily harm allies, try to use controlled power attacks. With over-healing, you'll have more HP than a Drunkard!
When your shield starts to turn red, its going to bust which will stun you for a couple seconds leaving you vulnerable.

Against Scoundrel:
You'll have trouble catching this class, getting really good with shield throws will be your most critical skill here. If you knock them down you can easily finish them with a whirlwind. They'll have trouble with their daggers against your shield but you'll be easy to bomb and blind since they're likely to leave a decoy into your attacks. If they daggerlunge away its probably best to find someone else to fight unless a Huntress/valk can pin them down for you. He'll have trouble using his heavy attack on you since your quicker attacks can interrupt him.

Against Valkyrie:
You're a pretty good match here, note that the valk outranges you and will likely create barriers to keep you back, plus they can disengage. Landing a skill combo on them is an easy kill though, and they probably dont want to be locked into close combat with you unlike other classes.

Against Drunkard:
Slow attacks are easy to block, when you see him ready to throw a barrel, jump sideways to try and avoid the stun. If he tries to body slam you, you can just lunge behind him. Save your whirlwind for when he drops his healing keg, you'll want to DPS it down fast. This guy will have trouble getting away from you, stay on him. His attacks cant be interrupted, so try to use heavy attacks.

Against Huntress:
Her skills can freeze you through the shield so only block if shes doing regular shots, if you see her aim into the sky, move out of the way. This is a class thats almost doomed if you get ontop of them, whirlwind will almost kill them alone. Expect them to jump away, save your shield throw or lunge to catch them (most likely shield throw, as you may be frozen.)

Against Raiders:
Try to open up with quick attacks, successful hits will interrupt them, if they shield up then do quick-quick-heavy attack combo but try strafing while you do it since a Discuss could be incoming. Try to save your lunge until AFTER they lunge you, then lunge them in the back. Try to hold onto whirlwind, if you see their shield start to turn red thats when to Whirl, the shield will break causing them to be stunned.

Against Highlander:
how the hell should i know

Against Shaman:
use your weapon on him

Against Giants:
run away?

Against Forgemasters:
pray.

Final thoughts. This class is 30% better with the Axe, but i'd try to avoid using him in bot-heavy matches.

Screw this guy, hes so fun to play, god i hate him, hes great like that. Very good in objective maps, since he can quickly cover terrain. His daggers are great mid-range damage, but hurt team mates a lot too so try to avoid "helping" allies too much. The throwing daggers apply marks on the target, when you use your heavy-attack on them it will detonate these to deal bonus damage. If at all possible, score a few hits on a target and move in for heavy attacks, this can quickly kill most classes.
The sticky bomb does friendly fire too, and you can kill yourself with it if you're not careful. Its easy to stick big guys or use it while retreating to deter chasers. Or just stick it to your allies because you're a scumbag arnt you? Its a great opener on stationary targets though.

The taunt is also a stealth, its extremely effective on basically anyone since even destroying it from range can blind you, and you can drop it while being attacked so your foe cant even avoid its punishment. This is your time for free damage or easy escapes. It can also block stuff like the shield throw.

The dagger lunge is extremely handy for mobility, you can quickly escape most enemies, or try to finish off a wounded enemy from a distance, since it also detonates Marks on the target.

VS Raider:
Keep your distance, be ready to dodge his initiate skills. Only move in for a heavy attack if it will be lethal, otherwise his spin is too dangerous and his left-click attacks interrupt your heavy. It can be dangerous to run away from these guys unless they've already used their skills. Not a good idea to bomb them, they might close the gap and take you in the blast.

VS Huntress:
Clever huntress can pin you down and kill you with the right combo, decoy to blind them is your best protection. Keep your distance, finish them off with Lunge. If you get the jump on them you can kill them extremely quick. If you see them use their Shift-jump, thats when you're free to engage up close.

VS Drunkards:
Usually an easy match up, they're slow and easy to hit, they can charge into melee range kind of quick but their slow attacks make it easy to Decoy blind them. Stack up a lot of marks before attempting to melee them. Bombs are also easy to sticky on them. You can ignore the keg and burst them down. Should be easy to dodge his slam/barrel.

VS Valkyrie:
These can be tough if they lock you into an area, they can use their shields to negate your daggers in many situations and their long reach and mobility lets them chase you. Even if you stealth, they could trap you in a dome and find you. Try to avoid

VS Scoundrels:
Soften them up with left clicks and finish with heavy, makes very quick work of them. If they decoy/blind you, just stealth yourself.

This is a kind of tricky class, very nimble, good range, strong support but great at taking out certain classes. Not recommended for new players! On objective capture maps she can use her dodge/flight to easily reach objectives or ales. Always use your Q on allies, needs aimed a little bit but provides a damage absorb shield, very useful for squishy classes. Pairs well with huntress to provide barriers for.

Her E ability puts a wall infront of her, it has a cast time so keep facing the direction you want it to be. Enemies cant pass it or shoot through it but AoE can still get through. Good for blocking off enemies in alleys or preventing them from flying back onto the map in some situations. Enemies can melee you through these barriers, but you have more range.

Her shift lets her fly in the air, this is great for getting around and taking objectives, hitting shift again sends her to the ground slamming and creates a bubble dome that is similar to the wall, enemies cant pass it. This is what you'll use to engage scoundrels and huntresses, you can kill them before they can get out.
Her power attacks tend to have more range, especially the third one. Good for mitigating team damage. Her mobility lets her easily escape most bad situations and find health.

VS Raider
Best to avoid, fight in groups, let others handle him. Hes mobile enough to follow you and can burst you down with skills and just generally win most fights. Against bot raiders though shes very OP, just wall up and melee them.

VS Huntress
Hunt her down, take to the skies and dome her! If she locks you down, put up the wall. Should be your easiest match up.

VS Drunkard
Drunkard can kill you much faster than you can kill him, even your range wont be much of a saving grace. Try to hit and run since you're more mobile. He can body slam you out of the air.

VS Scoundrel
Another target to look for, get him in a dome and dont let him escape. If he bombs you, try to stay close so it'll hurt him too. Hes faster than you but you're generally more mobile.

VS Valkyrie
Unless trapping them in a corner or edge, you dont really need to use barriers, this will just be a stab fight, try to get power attacks in.

Very fun ranged class, very nimble. Feels OP in big numbers, all that mass slow/freeze. Try to open up with a charged arrow if you can to slow your target, save your skills for the most part. Your Shift skill is great for locking someone down, you could even move into melee range just to lock them down with it, then easily land your E and Q, this can kill many classes as a raider cannot block while frozen. Your left-click arrows have greater range than skills, remember that.

VS Raiders
Always open with charged arrows from as long as range as you can, from a medium range they'll probably try to discuss you then close in. Dont use your Shift or E skills too quickly, but Q is okay to use from distance. If they get close, THEN use your shift-leap to root them, and the E skill while you're in the air (using Q in the air can sometimes cause collission problems in tight spaces) this is easy to combo and will give you few shots at them. Just hope they dont discuss you before you get your E off.

VS Scoundrels
Usually easy. If they get close with stealth just shift-leap and do the same combo, they'll be dead before they thaw, even if they decoy they'll be frozen in place. Your Q ability is great for trying to hit them after they've stealthed, and Shift will also reveal them if they're close. Look for frozen feet.

VS Drunkards
Big easy targets, easy to land your E on them, get some free hits and get up close, then use your shift-leap to root them so they cant bodyslam you/escape, then drop Q on them, if they drop a keg they'll be sitting in your AoE and you can out damage the keg with the combination of damage.

VS Huntresses
3 fully charged shots will kill, thats the best way to do it. Save your Shift and E skills, Q is good to use though. E and Shift are too important for closer range defense.

VS Valkyrie
Your biggest enemy probably, they can fly up and then crash on you creating a dome you cant escape, they can stab you from the outside. You can still use your Q inside the dome to deal some damage, but your best bet is landing your E shot at close range inside the dome, then try to DPS them down with left clicks. If you cant, shift-leap before she thaws, the dome should be down soon. Try to shoot them out of the air if you can, they float a lot.

The big support class that packs a punch! This guy can really be hit or miss depending on how well your team mates stick with you. Your basic attacks cant be interrupted but they're slow and can be hard to land, easy to block. The power attacks give you a speed boost so start using them to get around the map faster, watch out for smacking team mates. They push enemies back too, so they can be hard to combo. You can also start over-healing allies with your right-click kegbeam, try to top them off. Your Q ability is an AoE heal that can also top off allies. Your E is a strong forward aoe that stuns and shift is a mobility/escape/damage skill, can get you over map obstacles or crush fleeing enemies.
Your body slam wont give you over all objects, use this to your advantage to cause you to jump straight up and body slam down.

VS Raiders
They're hard, they can kill you fast with a couple heavy attacks and whirlwind, their discuss probably wont miss you very often. Try to use power attacks on these guys since they have better range, if they whirlwind and you power attack them it'll send them flying away. Ditto with Lunge, they might fly over your head if you hit them high enough. Power-attack-normal attack is a decent combo. If a raider is blocking, use your E skill to break it and get a hit in, or try to escape.

VS Huntress
Try to save your body slam for a FINISHER, not an initiation. As soon as you get close they'll shift-leap away and your bodyslam wont get you anywhere (unless its cramped and they land next to you) if you get rooted, drop your keg. You CAN kill this class in a few hits, if possible open up with your beer-wave E ability and a power attack, then get away before they shift-leap. Finish them with a bodyslam.

VS Scoundrel
Another class you can squish in a few hits, if they start stacking too make Marks on you prepare to be melee'd, you probably wont be able to interrupt it unless you use your beer-wave. Stay close to your keg for healing. If he blinds you, thats when you should drop keg or bodyslam somewhere just to get away.

VS Valk
Not really much of a threat, she'll have trouble out damaging your keg, and you can kill her in a few strong hits, she has no damaging skills to burst you with. If shes hitting you and your hitting her, you'll win.

VS Drunkards
Its hard to burst down other drunkards with the kegs out. Try to save your beer-wave for destroying their keg with, and save your body slam to use right after they use theirs. Use power attacks to knock them in the air, may cause their attacks to go over you.