Didn't even bother looking at the challenges, didn't base my game play around them.

Didn't affect my enjoyment of the game in any way. Hell, I don't think I even looked at my actual score (I'm going to stop short of saying that I didn't even know that there WAS a score at the end; I like to think I'm more observant than not noticing something like that), so really… how much could it have mattered?

Rather eagerly anticipating Book III, personally.