I think a lot of people had the initial kneejerk Pandas reaction.
Once people got into the expansion, a lot of people really enjoyed it, but some could not get past the theme/pandaren, and 14 months of Orcs was harsh for the orc haters.
Personally, Legion > MoP = LK > Cataclysm > WoD > Classic >>> TBC. I'm ecstatic with Legion and hope they keep it going well. Once WoD was out, I never though they'd top LK/MoP.