Shabdez: I can ensure you that mouse + keyboard work perfectly fine in this game.
I concur.
This was gifted to me for Christmas; and I just started playing it the other day. I only have the mouse and KB; no controller, and it works great. You can even bind the same key to multiple actions if the actions don't conflict with each other (for example, "Loot All" on the same key as "Interact" [with NPC, readable, etc.]), and non-WASD works fine (I don't "do" WASD, preferring the Arrow Keys to move). Also, it warns you if you bind a key to multiple "conflicting" things (and what "thing" it is).
Works very well, and the game is very enjoyable and engrossing atm.
(I'm not very far in, but I'm done with both the beginning "Tutorial" area, and the follow-up nicely-larger area I refer to as the "starter area" [named "The Embrace" I think], and am now out in "the world at large". Has good stealth options too - which, for me, is a preferred way to play).