Well, this is one of my favorite games this year. But, I will say, if that is going to be a gamebreaker for you, if that is your primary fun, then you will hate it.
I tried the prologue on KB/M. couldn't do it.
tweaked my character, switched to 360 controller, and it was much better. I don't think there is any way to "fix" keyboard and mouse for this. combat, and the design of the skill system, was all about 8 buttons on the gamepad.
There are less skills, and even within those skills, you have stacked effects (basically--what would have been 2 or even 3 skills in DA:O or other comparable games, is combined into 1 skill in DA:I). Honestly, I don't think that's a horrible design choice, but I can see why people would balk over that. For one thing: passives tend to be far more powerful than active skills.
Mages are a good bit neutered in comparison to most RPGs
So, build design, far beyond combat, pretty much says that there is no hope for KB/M in this game. Now, people still use their KB/M--because they are stubborn, I guess--but even tolerating that means that you accept only moving in cardinal directions which, to me, is revolting.