I play WoW on and off for a few months at a time. Usually get bored by my friends power levelling away so I end up soloing. WoW sucks when soloing.
I have a 35 Druid, 16 Paladin and various other characters I never play on the Eredar realm.
A good portion of original members from The Company are playing WoW. We're Dynasty on Drak'thul server. I'm currently a level 41 Pally, but I'm moving up. Our guild likes to do raids, but I have yet to participate. I wasn't sure I would like the fantasy setting, but I'm having a lot of fun. I like the way the story progresses as you level up.
WoW vs. MxO = Apples vs. Oranges, I think, at least as far as the intended audience. I like both games. I do hope the devs are playing some WoW, because there are some things I'd like to see in MxO.