I have played WoW and quit at level 30. It got really boring; every quest is just variations just kill X monsters or collect X items or deliver this & that to someone.
Even when reaching a 'new' area it feels the same, just higher level monsters populated there, etc. The item and talent system is bad also, it's just like Diablo 2 all over again (nothing against D2 though).
Hoping at least Vanguard can bring some more innovation to the MMORPG table...