Adding to this (and bumping in the process) I'd really like, though this is my personal preference, if XP gained and numbers in general were kept to low digits, maybe even single digit. Bloodlines had you gaining 2 or 3 exp points per objective for the most of the game and it worked really well because of how the character system works. Meanwhile games in which to gain another level require me to gain GORILLIONS of exp points remind of MMOs and their audience, kids that want to see huge numbers.