Even with the controls fixed I think it would still be hard and 2) the lock-on feature is just entirely broken with mouse and keyboard. There's something about trying to navigate and fight using a mouse that just kills this game. The two worst things about the mouse/keyboard combo are: 1) The mouse is really jerky. It's hard to explain, but I mean it - get a controller. This is partly due to the lock-on feature, and partly due to how shields work in the game.
Even if the mouse and keyboard worked better, the controller still has the best possible mapping. I know some PC gamers are averse to controllers, but this game is designed for one.
Once that was fixed, it runs like a charm. I had a hard time getting the game to recognize mine, but it turned out it was a driver issue. Whatever you do, if you play this game on PC, shell out the extra money for an Xbox 360 (wired) controller. I know that From said the mouse and keyboard would be bad, but I didn't expect that it would be this bad.
The hunter build gets you a bow early on and good average stats.