I'm a casual raider 9/12 N, and I really enjoyed this tier of raiding.
I started to play WoW on ICC +30% and never felt this good when I kill a new boss. Even if I didn't kill the end bosses, I think the difficulty of the encounters is really good. If you play any other game (from Tetris to WC3 or a different MMORPG) you won't win it playing bad (if you do then the game is shit), so is WoW now.