My complaints/feedback/bitching, in no particular order. I should note that I'm playing a Heavy Weapons Crusader.
Items other than armor and weapons are pointless, interchangeable statsticks with no intrinsic value or usefulness. What's the difference between a Signum and an Eye Implant? Absolutely goddamn nothing, that's what. They're just statsticks that hold random enchants of negligible value with no rhyme or reason. Why do my Frag Grenades give me hit points? Items should be consolidated into weapons, armor, and a few wargear slots with items that have some meaning to them. You want to have Eye Implants? Fine. They should give me things like crit chance or a chance to spot traps or increased weapon range, but they should do SOMETHING that seems even remotely relevant to what they are.
The levels are pointlessly large, empty, and repetitive and it takes entirely too damn long to traverse them. For the love of the Emperor give us a damn sprint function. If you don't want us to have an escape then make it not usable in combat, but walking through the levels is a literal tedious slog.
Weapon switching should not start with abilities on CD. It means you will NEVER switch weapons in combat unless your other weapon is overheating. It robs players of the ability to use the appropriate tactical tool for the job, which is why weapon switching exists in the first place. The only time I've switched weapons in combat is if my primary is overheating and I need to shoot things still, and then all I can do is spam left mouse.
In my first mission, I didn't realize that I had limited Frag Grenades until I was impotently hammering 3 and nothing happened. Only then did I see the absurdly faint 0 indicating I was out. Then when I found a supply chest I noticed the number. Change the color so it's actually visible.
Why does my 4 ability have both a resource and a CD? Also the resource is useless as it's used ONLY for the 4 ability. Why even have it? Just have it on CD.
Crafting seems pointless if I can only craft Rare items. Also please remove the damn crafting times. What is this, SWTOR? I have to wait an hour to craft my Demolition Armor only for it to have utterly useless enchants then have to wait another hour to basically reroll it? It's pointlessly frustrating. There's already a resource cost to crafting so you're gated in that way, don't also time gate arbitrarily.
What in the Warp do all the damn numbers mean on items? Do Attack Power and Defense Power actually DO anything or are they basically just ilvls? When I do item comparisons I get +/- offense/defense and those numbers seem completely pulled out of someone's ass. They relate to nothing concrete and might just be RNG results for all I know and for all the good they do me. They confer no useful information whatsoever.
Killing enemies is pointless and provides no intrinsic benefit to me other than them being obstacles to mission success. This is an ARPG. I should WANT to kill enemies. I should want to kill them because 1) it should be fun (it's not) and 2) because I should get something for it (I don't). I'll put the fun issue aside for now because that's entirely subjective, but enemies should give individual XP and have better drop rates. If I see a pack of enemies that I don't strictly need to kill I should WANT to kill them because they provide me with incremental bonuses (XP) and a chance for something good (rare drop). Right now there is zero motivation to kill enemies other than that it's necessary. That's a terrible characteristic for an ARPG to have.
Inoculators without red slots are the single most pointless item ever put into any video game ever (yes, I'm being hyperbolic, so sue me). They are instant vendor/salvage trash. Who in the hell would want a healing item that can't heal? The combat bonuses that the yellow slots provide are laughably pathetic and come at WAY too high a cost to ever justify using. The green bonuses might be useful if they didn't come at such a high cost. Two red slot Inoculators are the only ones worth using. Now if we could have multiple Inoculators, that might be something. One for healing and one that's basically a combat stim. Then the other color slots would have value.
Cover is a worthless mechanic other than to recover HP/Suppression Resistance because you can't do sustained damage while in cover. It's far more efficient to just stand in the open, take hits, but dish them out in return, then duck into cover when the enemies are dead to recover HP/SR. Fighting from cover is inefficient and counterproductive.
That's all for now. I'm sure I'll think of more.