Phasing still sucks.

MoP has a lot of ground clicky collects that aren't group-wide. So you will be grinding quite a bit of questing if you go that route.

Follow has been removed as a mechanic in BGs. That rules BGs out.

A very unhealthy number of mobs now do ground slam effects that mean you need to move around a lot more than you used to. Timeless Isle is a good show of this.

5 man dungeons are easy but they really didn't put much work into the dungeons this iteration. WoD should be better.