I started with KB&M, went to a controller, and now I'm back to KB&M. Sorting the inventory is so much easier with drag and drop, as opposed to X>Hold item>A. I had some misclicks in combat for sure, but it's been much better now that I pay attention and zoom in/pan around to get in the best position. I also like being able to pan the camera to an area, then clicking to go there, rather than tooling around with the analog stick. Everything just happens quicker being able to use a mouse, even though the implementation isn't perfect.
That being said, the controller scheme in this game is damn good, and I'm glad console gamers (and those on PC that prefer it) can play a sweet turn-based game without struggling with controls. I still use a controller when in-home streaming the game to the living room or whatever.
I restarted a while back, and a lone wolf 2h fighter type (with 7 int and 2 points in witchcraft for the buff and summon) and 2 glass cannon mages party is just making classic so easy. I mean that in a fun way. The mages don't do much damage, but they can really lock enemies down, while my fighter buffs himself up, walks around stabbing things on the ground for huge damage, or summons a skeleton as a meat (err, bone?) shield when needed.