In some regards better than cata, in many other regards the worst expansion to date. I've listed the reasons why before but I was infracted for it, I guess criticising WoW is not tolerated here. Generally the game has shifted massively away from being a sandbox game - huge emphasis on daily quests, dungeons and raids are more linear, bosses tell you exactly what to do during a fight, pvp has been homogenised and dumbed down. I get pissed off when I log in because I feel like I'm a rat running on a wheel, doing exactly what blizzard want me to do. I can't make money from old raids anymore, I can't create original specs, I have less diversity in playstyles. For some people I suppose they like being told what to do, but for me I'm out.
What makes me sad is that I bought MoP WANTING to play it, I really want to play. I just hate how blizzard have pushed people like me away, and I'm not the only one, most forums other than MMO-champion tend to side with my point of view.