WoW was amazing because PvP and PvE were always solid... that wasn't the case when cataclysm hit... their class balancing was horrible... every damn patch there was constant changes to almost every ability. You might think the game is still amazing... but not only do I have facts to back up my opinion, but when's the last time you saw WoW winning awards? It used to win awards in TBC/Wotlk... back when PvE and PvP were consistent and not unbalanced...
That's funny, because Cataclysm had my favorite raid tier ever (tier 13: BoT and BWD) and another very solid raid tier (tier 14).
Doubly funny, TBC had some of the worst PVE balance problems ever. Tier 5, at release, was absolutely broken. A good chunk of tier 5 bosses weren't killed in their launch versions (Al'ar, Morogrim, Solarian, Kael'Thas, and possibly a few others in SSC). Even Karazhan, probably the best raid in WoW history, had several balancing problems. Nightbane, alone, went through somewhere around 3-5 revisions post-launch (let's bring as many paladins as we can so we can BoP his skeleton spawn ability!) and Shade of Aran was the fight where you swapped someone out for a second warlock. Oh, and who can forget the Sunwell debacle? Let's bring as many shamans as we can so we can rotate them into the strongest DPS party for heroisms... and let's not bring any mages.
Yeah, TBC sure was a shining example of PvE balance and consistency.