Gonna try to not make a wall of text, Emperor give me strength. First, some good before the flaws.

1. The game with 3 coordinated properly equipped brothers feels fine, sure some pain points but all games have that and hopefully they will be ironed out. 

2. PvP is fun, sure shocks needs some tuning, spawn flips needs a cooldown timer at least, but overall once you learn how to fight each class its decent. 

3. Item progression and perks overall are fine, some things need tweaks (looking at you Oculus), but again nothing of major concern.

4. Overall weapon tweaking since 4.0 has felt great, and the new Neo-Volkite pistol is fun if nothing else.

5. Lethal has been a fun change of pace for my premade, i kinda miss the armor tethering system but its previous implementation wasn't great, so glad its back on the drawing board.

Now the point of my post and the balance issue. 

1. Bot controlled AI is horrendous. Their current state is almost better for them not to be there, you can't reliably focus fire them onto a target by marking, they only do decent against Minoris and Majoris (especially in higher difficulties), as there has been post after post about their damage (or lack thereof) against Extremis I won't beat a dead horse on that. They never reliably execute enemies, their targeting priority AI and their weapon use priority AI is hilariously horrendously bad. They walk past executable enemies, stick to their secondary for far too long, ignore call in enemies, use equipment at super bad timing. I get we don't want them to carry the player, but the player shouldn't have to carry them.

-Why is this an issue? Well sometimes we want to play alone, sometimes we want to test and do things that would be a negative game experience in a pubic lobby, sometimes people might not have an internet connection, and sometimes all our friends aren't available. I'd rather not feel like I'm being held back by the AI bots. Give us something, buffs to the player when entering with bots, difficulty or item/ammo drops that scale with the players when accompanied by bots. Tweaks to allow them to fire at marked targets as a bias. Something aside from unkillable rezbot zombies the AI teammates currently feel like. 

2. Enemy and item spawns across difficulties: a 2 part issue that compounds one another. This effects both public multiplayer and solo bot play. Certain areas on maps (of all difficulties) where Extremis can spawn should have a guaranteed ammo resupply if the Extremis is spawning there. Yes, we don't want the maps to feel too repetitive or have a sign (ammo resupply) saying mini-boss here, and having various things spawn in multiple possible spots helps with this slightly, but it feels way worse to kill the pre-spawned enemies, then the wave(possibly a call in as well), then a couple Zoanthropes, and then a Carnifex pops out, all before you have a chance to restock off anything but random ammo pickups and perks.

-This is an issue because it makes certain weapons/perks/classes feel horrendous in comparison to their alternatives. It's the reason why heavy/sniper multi melta/las fusil/stalker bolt for example are so prevalent and touted as "the best options". I have seen people leaving matches on everything from Average to Ruthless simply due to loadout/class choices. While this is a player behavior and isn't directly the developer's fault, it is an effect that has come about in part due to the difficulty via poor balancing issues. 

3. There is no feeling of progressive enemy escalation as you increase difficulties since 4.0.

-Every single mission on every difficulty (sans lethal) is the same. Your going to see at least 2 Zoanthropes, a Ravener, a Lictor, and either a Carnifex or Neurothrope. With little to no variation except order and location. (Or for chaos 1 sorc, 1-2 Occult Terminators, 1 Heavy Terminator, and a hellbrute possibly) IO have had Average and Substantial runs (both bot and multiplay) that were harder than Ruthless as far as enemies spawned. This leads it to feel that all you get as you go up in difficulty is enemies just feel like they are there to waste more of your ammo, to artificially increase the difficulty due to scarcity and class/loadout choice. This isn't a horrible thing, it teaches you to conserve ammo and utility, utilize gunstrikes more, utilize melee more, and generally "get good", this being the currently only source of difficulty curve feels very bland, repetitive and boring. Its not a good state to have when trying to avoid the game feeling repetitive. 

Now that i failed at not writing a wall of text out, lemme just say. I still enjoy the game and 100% recommend anyone interested in the 40k world or horde shooters to play, I simply want to give some feedback and hope the game keeps improving.