I played from late Vanilla Beta and I quit with the release of argent tourney. A one room dungeon and a ton of dailies passed off as content was infuriating. Particularly after how great Ulduar was.
I came back in the middle of Cataclysm to see if things got better. The removal of player choice by forcing people to the end of talent trees and the mastery stat discouraging armor mixing, combined with starting in the middle of an expansion and people expecting you to know the dungeons had me not renewing my sub.
I then tried Pandaria during beta. I found there too be too little content and too many dailies, repeating my issues with Argent Tourney combined with the increased reduction of user choice through class tailored quest rewards and a top tier of glyphs renamed as talents had me not even giving this expansion the time Cataclysm got.
At this point I occasionally activate the game when I get a free week. I don't plan on spending money on WoW till there's some character management decisions returned to the players.