Hrm, I don't really remember that was. Maybe when it first came out a lot of the ideas seemed neat [and I'm not one of the type of people to get upset because some class or race wasn't or was put into the phb] and it looked fun to play.
After playing it for a little while though, I came to realize that I enjoyed tinkering with 3e more than 4e [it's like in the process of their simplification, they took out all the fun stuff to modify or create, namely creatures and Prestige Classes] and that for some reason, I just don't enjoy DMing 4e as much as 3e.
My dislikes I've found are only things I can vaguely put my finger on because I haven't played 4e for a while, so it's sort of difficult for me to figure out how to change what I dislike.