Well, I can't really say what I like most - but I can say what I don't like :
It irritates me *ervery time* I play a game based on (A)D&D+ , it irritates me beyond BEEP that I can get a feat or a new ability only after 3 or so levels (?), and seem to be stuck with the same "strength" like forever. I'm very sure I play it wrong, because most people seem to like it, but to me it feels as if I have the same hitpoints & "strenth" / "power" throughout the whole game (BG, for example), and get only a few extra points via "a weapon +1".
I still wonder why it feels so "wrong" to me, and what I'm doing wrong there … I guess that I'm too much used to the character progression system of TDE …
What I like, however, is, when a character gets some "extras" during character progression he or she has not asked for … It always feels like a "nice surprise !" to me.