Yeah the movement of the game doing attacks is kinda whacked (I found myself much prefering Witcher 1 and am hopeing the deliver on promise of improved combat in TW3) but its nothing game breaking.

I went out and bought a game controller for the PC and TW2 combat became much much much easier.

Really only frustrating thing is the Kayran
But thats QTE and those have been 100% removed from TW3 according to CDRed.
And once you know the patern of the QTE is all pretty basic on any difficulty.

Gameplay is not broken
But OP, if your having trouble then lower the difficulty setting and get better at it