Allright, with 40 hours into it, and multiple maxed Warbands, let me take another rant at this.
First and foremost, as loathsome I feel to admit this, the difficulty is actually not as bad as you might think at first glance. I've reached a point with every Warband except sisters, where I'm going for Brutal / Deadly missions only, because the reward is so much greater and normal / hard missions actually do feel like they're cakewalks. I think there's a sweet spot, where your guys reach a stat / skill level, where they are very good at the specific thing you built them for. The AI on the other hand seems to be spread out fairly evenly.
My Skaven Warband was built completely around Warp Posion (For those who have no idea what that is, it's a poison applied before you actually engage, which lowers the enemies max OP, basically denying them attacks). I had one meele rat with high resistance and Warp Poison, and one designated range guy also with Warp Poison. The other two were built for critting and casting respectively.
That Warband had a 97% Success ratio, and a 1270% K/D.
My Possessed Warband was built around Glass Canons with high Dodge ratings. I dont have the exact numbers for them, but it was also around 90% success ratio with a similiar K/D to the above.
Now, I'm not saying this because I think that I'm that amazing at the game. I wanna highlight that there are a LOT of builds that basically turn the game really easy, and just highlight the AI issues even more. The AI is close to being completely predictable, to the point where you can build your Warband KNOWING that camping, holding out in buildings and abusing Choke points will almost guarantee you a win, barring a bad roll streak ofc.
There are however three features in the game, which basically add random "You will now arbitarily get owned" moments.
The first one's demons. If I'm not completely remembering it wrong, you start seeing those at Warband rank Level 6 and only on brutal or deadly missions. They spawn randomly around the map and you NEED to focus them down with at least 3 -4 guys, to even have a LITTLE chance of killing them. They come with a massive hp pool of over 600, have 3-5 attacks (They can and will frequently kill even heroes with a focus on toughness in one turn) and they also induce Terror tests, making them even harder to kill. IF they spawn, they basically stick to their starting point until they can see the first guy that comes into their sight. Basically, if the Demon spots the enemy warband first, you get a free win. I've had a good chunk of missions where I could run around looting freely while one Demon pounded a 6 man enemy warband, completely on his own. On the other hand, if he gets to you first, you have to pray they dont one-shot one of your guys and then bolt. The only real disadvantage demons have, is that they cant climb. So you can completely nullify the problem by finding climable high ground, promoting even further abuse of the AI.
Second one's ambushes. There's a 10% chance (It was 15% before the current patch) that you get an Ambush on route to your mission. They can be either in your favor or in the enemies favor. Basically, the ambushed Warband has less starting OP and SP, less chance to hit and lower melee resistance. The Warband doing the actual ambushing starts out with all of their guys in either Overwatch or ambush stance. There is NO way for you to influence this in any way. You cant send scouts, you cant choose to abort, you cant even voluntairly rout when it happens. It's just a plain "You get arbitary disadvantages NOW."-moment.
And finally, there's the market rotation. It's supposed to give you a new stock of items every 8 days. But the stock can get raided on route, so you get NOTHING new. If you get unlucky with initial equipment, or some of your stuff get's stolen, you REQUIRE that market rotation to get back into the thick of things. It's just another random "haha nothing for you!" moment.
So what does all of this add up to? It promotes restarting Warbands over actually trying to stick to the one you have early on. Heck, even permanent injuries are basically meaningless. Absolutely everyone I know will just drop the guy that lost an arm, or a leg or whatever, and replace him. If they cant because of money, they restart. This is later nullified by you having such ridicolous stacks of cash and gear, that even the death of a Level 6 Leader means absolutely nothing. Just get a hired sword, and if you cant, stick to one or two normal / hard missions to level a new one. Basically, you keep restarting until you get a decent couple of missions early, and then the game turns into "Ai Abuse Simulator 2015".
The AI's rating is based on your rating. So let's say you had 5 guys, and one of them dies. If you keep running missions with 4 people, the AI will stick to 4 as well. So there isnt a different feel, there is no impact. There isnt even a real punishment beyond Gold. And even that just means either restarting if your Warband is young, or just drawing from the 8k you have in your bank later on.
The Dev is WAY too obsessed with the whole "WE WANT TO BE HARDCORE" thing, and that echo chamber, maliciously calling itself "Steam discussion" is happily telling him how cool he is for doing it. The game is BUILT for you to get owned out of nowhere, without realizing that it doesnt actually matter even one bit. It's obsessed with throwing deaths and permanent injuries at you, even tough they dont matter at all. Removing "save scumming" didnt fix anything in this regard. It just added time frustration to the mix of stupid design decisions.
And of course, all in the name of Multiplayer. Someone please, for the love of all that is RNG, send that guy a letter kindly explaining that a LOT of people couldnt NOT care less about your stupid, unbalanced, boring Multiplayer. There isnt even a programmed Multiplayer Campaign in yet, and they are ALLREADY shoving it in your face. All it needs is a checkbox "Singleplayer only", with alt+f4 or save scumming, and everyone is happy. But no, let's subscribe to the "git gud scrub"-crowd.
To put all of this in a short summary. This game is trying it's very HARDEST, to be hardcore, to throw arbitary deaths, injuries and other stuff at you. And none of it matters even a little bit. It's been a while since I've seen so many bad design choices in such a short amount of time. There are still places in every Level where the AI will ignore collision, or get stuck on corners. But no, people where not accepting our random difficulty hardcoreium! Let's fix that RIGHT away. Wanna know where the difference from this to Dark Souls is? If you die in Dark Souls, it's YOUR fault. If you get owned in Mordheim, there's a good chance that it was just the game randomly deciding that you were having too much fun.
This Dev needs to get his priorities straight. There is a good game in here. But it's getting closer and closer to being buried beneath lazy difficulty and focus on the wrong things.