The issue with the kb and mouse bits is that I find the climbing and sprinting bits don't work as well as with a controller. You just don't get the same range of motions on a keyboard, unfortunately.
Yeah, you're kinda limited to key directions rather than a smooth analogue set. I generally use the mouse for direction, so it's pretty smooth, and the keyboard for sharp turn or 180's.
So far I'm finding it fairly straight forward with the KB+Mouse controls. It took me a bit to get used to the keys especially in combat. My mind is still kinda mapped to the gamepad buttons since they're directly matched with the diagram on the top right. It wasn't until I reverted my perspective to the Prince of Persia style that I got a better grasp on it.
All in all I think they did a great job of making it work.
Speaking of the combat, from the Gamespot review and many player comments I gathered that the combat is supposedly difficult and generally a bad idea in most cases.. Honestly, the combat is frickin' easy. It's just a matter of timing. No matter how many people you're up against you're only ever attacked by them one at a time. I like the counterattack system I just wish there was a tad more variety to how my enemies attack me. As it is, all the fights end up being essentially the same thing: guard, wait for attack, counter, next. Repetitive, but never fails.