To me, the whole game feels like a major step back in quality from prior titles. My personal issues with the game are listed below. I believe addressing some or all of these would benefit the game greatly.
Very low map count
poor quality campaign (slide show cutscenes, disjointed storytelling, missions feel ripped right out of the book of generic RTS)
coop removed from campaign
last stand removed
Few Races (I hope the first new race is free, seeing as how one race was removed compared to the 4 we got in both previous game launches)
units can die in a blink of an eye to click abilities and stiff breezes
no retreat button, which I've grown to love in other relic games
No veterancy system or leveling in game for line units or elites
no cover system (i dont count the 2 or 3 bubble shields on the map.)
a disregard for lore (imperial guard fire star wars blasters, space marines die as quick as guardsmen, plasma guns, gabriel angelos flipping etc.)
uninteresting unit upgrade tree in game (the main choices are upgrade damage and upgrade defense. It was boring back when I replayed Warcraft 3, it's especially boring in 2017)
Really uninspired unit voice acting/lines. Compare the dreadnought and space marines from all 3 games. Video examples included and
Music/sound effects aren't exciting enough compared to prior games. The dreadnought autocannon from dawn of war 2 sounds like it packs way more punch than an imperial knight in dow 3.
I miss units feeling like individuals in a squad, like from other relic games. In dow 3 they all march in near lockstep with the same animations. So boring. Unless i didn't notice it, they also don't seem to have minor variations in battlescarring or uniform.
The graphics (to me) don't seem like an improvement over dawn of war 2 which came out years ago. I expected better from this developer.
Big battles feel messy and hard to see what's happening amidst the light show. Really disappointing considering relic made it a point to state visual clarity as a major goal of the new art style. I might be more accepting of the art style if it actually helped with visual clarity which I personally don't think it does (especially when the light show starts)
No sync kills (I get that it was for balance of competitive multiplayer. But it was iconic to the series, and I don't see why it couldn't exist in singleplayer and be an option for casual multiplayer/vs AI modes)
I don't like how early hero units start out absolutely devastating and then sort of fall off as the game progresses. I would have preferred a system more like dow 2 or warcraft 3 where your heroes can level up, get upgrades, and be relevant (but not devastating) throughout the match.
Something I really liked about dawn of war 2 and 1 is that i felt like hero units supported my army, whereas in 3 I feel like my army supports my hero units. I'd like if it were switched back.
I could probably go on, but I'll leave it here for now.
If i had to pick the issues that MOST bother me from this list though?
It's that I don't care at all for my line units. That's primarily because they have boring voices, don't have much personality, dont gain veterancy, dont act as individuals in their squad and they die in seconds. I want to care about my units. I want them to sound and look cool. I want excuses to keep them alive. I don't want to throw them out like used tissues. I CARE about my squads in Company of Heroes and Dawn of war 1 and 2. If i lose a vet 3 squad I'm legit sad. It's one of my favorite features of relic games. I miss it here in dow 3 a lot.
Thank you for reading