I have to say that I personally really like DnD 4E both as a DM and a player.
Player-wise I enjoy the fact that I can customize my character in a wide variety of ways without being useless or breaking the game and as a DM I was just sick of having to go over the 20 odd books of supplemental material to find what spell the wizard wanted to cast.
Wizards did take over the game in 3.5E, While running the City of the Spider Queen Campaign it was totally broken from the Sun Mage (prestige class) tearing apart encounters single handed with a fireball. I was really naive to let that class into the game because of the ridiculous bonuses the class had against Undead and Drow specifically. The whole thing bummed the players and me out especially after setting up the map, reading up on the tactics (not to mention plumbing the 20+ books for details on the NPC and players abilities), Setting everything up to be blown out in 1 round. My fault entirely for not checking on the details of the prestige class and trusting the player.
