I tend to be a sucker for dystopian settings with anime sprinkled in, this is no exception.
Albeit with some criticisms.

Grungy pixel aesthetics with Low poly models/environments, I like it.
It has a nice soundtrack, but really it's more like 1 fleshed out track with the rest being placeholder loops.
Also either I glitched out or some scenes just have no music at all, making it just awkward clicking through dialogue.

Main gameplay wise, it's pretty straightforward.
Defend a wall, here is a gun, get money.
Simplified into RNG card pulls, all you really need to do is stat boost and get a gun that does not suck.
This becomes very satisfying fast just watching the enemies pratically disintegrate under my upgrade shenanigans. Some guns are waaay better than others.

However, this simple gameplay loop, can get boring.
You can get a different experience cutscene wise if you get a collegue to fight with, some subtle interactions too, and breathes some life into your dormitory life, pretty much the only place you go after missions, but it doesn't really change the story.
Same conclusion and fate either way, thankfully for people wanting the achievements, getting all the endings is NOT needed.

An extra challenge mode where you can play as all the girls is nice, they even have individual quirks for some varied RNG gameplay.
It's a shame this doesn't mean multiple story modes.

I've seen this compared to a mobile game, and frankly that's not too far off, while you can move around, you never really have a reason to. (Although you should totally do that for certain BIG enemies) since you as the player don't have a health bar, it can be pretty easy once you are in the groove and have high stats. You can just imagine this game working through touchscreen alone.

I agree with any negative review review here, but that doesn't mean I hated it.
It's not perfect, but it's simple what can I say.
I'd say get this when it's discounted, but I wouldn't complain either way.