Okay got to level 10 and quite a few story missions; also going to ignore early access impressions and just keep it to what I think as a fully released game.
Graphics - some of the art is good, and they've done a nice job with the 40K themed iconography. That being said, it's really uneven and overall most levels look utterly bland and repetitive. I get the game is supposed to support infinite random generation but even by those standards I think it's poor, and frankly I think this whole concept was a mistake anyways (more on that later) since nothing else gameplay wise actually supports it.
Performance - I have a GTX 1080 and a i7 7700K so the game should run smooth, couple that with the fact it's really not the most impressive game in the first place, well given that it runs like hot garbage. There's times where it's smooth I guess but when there's a decent amount of enemies/action on screen it just tanks. And when it tanks it looks horrible...it's not just a minor slowdown/stutter but animations go to absolute shit I don't think I've ever seen a game handle slow down like this.
Sound - Pretty sub-par to be honest. A lot of the sounds are just plain bad, for instance the pew-pew of plasma guns which literally sound like something from a Saturday morning cartoon. Beyond the actual sounds themselves the engine behind them also is poorly implemented with sounds constantly stepping on each other.
Gameplay - Sluggish, clunky, and bland. There are moments where it can be fun and you can get into a groove, but the balancing of enemies is ridiculous. Some of the enemies are just colossal bullet sponges and you have to switch weapons to deal with them, but typically there will be a giant cluster fuck of enemy types and that mechanic is really clunky. They don't give you any skills, it's all tied to weapons, switching weapons puts skills on cooldowns, some weapons are clunky, just basically there's so much jankiness and needless cooldowns it's a hassle to deal with huge mixed packs of enemies. Cover mechanic is fine and personally I think it makes sense for the game world, it's not all that useful though.
Co-op - Only played a single match but it's terrible. Not only did it take ~20mins just to get in a co-op game, but when I finally did something is really screwed up with multiplayer balance. Enemies, even normal fodder types, were absolutely ridiculous bullet sponges. Then when we finally hit some bigger packs with tougher enemies it got to the point I just noped out and quit. There's no real benefit to co-op as far as I know, and if all co-op does is make an already sluggish and clunky game even worse then there's zero point. That's a first for me in an ARPG...multiplayer making the game even less fun lol. Once you take into consideration that this is an always-online game that they feel is almost a MMO in a sense it's just crazy. There's no trading, no hub worlds. One of the most poorly implemented co-op modes in any ARPG I've ever played.
Okay so all the above is pretty shitty and would be enough to sink a game I think. That being said, I am a sucker for even bad ARPG's and can stomach even the shittier ones if there's some fun to be had in the setting, character building, and item hunting. The bad news is the game completely fails at these mechanics as well.
Character building - Lame. Actually, beyond lame. Yeah there's a ton of 'skill trees' but they are the most pathetic skill trees I've ever seen. Almost completely consisting of +some infinitesimally measly % to a stat. Even the keystone 'skills' are pathetic and are like +10% damage for 5 seconds after using a specific type of damage. All skills are tied to weapons (each has 4), but they are all pretty much the same. It's either pew, strong pew, or pew pew pew. That is the lamest version of skills ever in an APRG. In the 10 levels I've gotten so far, and let me tell you those 10 levels are a slog to get through, the way my character played evolved in absolutely no discernible way.
Items - Already touched on this above but aside from the unimpressive (other than the fact it is kinda cool using 40K weaponry) item/skill system the items themselves so far are boring. There's 3 types of armor (at least for crusader), and they visually never change aside from some palette coloring. You do eventually unlock more weapons as you progress but it's a slow, grindy affair and I've been using the same 2-3 weapon types that entire time. Item stats are fucking pathetic with +1-3% attribute/stat modifiers that you barely feel have any actual effect when playing which is further compounded by the fact everything is scaled to you overall power level/mission level anyways. It is one of the blandest items systems in an ARPG I've ever seen.
For me the lifeblood of any decent ARPG is solid gameplay, fun character building, and a robust and rewarding item system. Compared to something like Grim Dawn it's just a colossal failure. I don't think there's much they can do here either, the systems they've implement are so poorly designed it would require complete re-writes to bring them up to par.