I think it’s one of the best games on the market, honestly. Thousands of hours of stuff to do, a lot of classes to fit every playstyle, almost a decade of gameplay refinement. I’m not going to go so far as to say that it’s all-killer-no-filler (any MMO is going to have a fair amount of dead time in it), but it’s still a lot of fun and I can’t wait for Warlords to come out.
That said, right this very moment might not be the best time to get started. Warlords is coming up, and there’s usually a big balance patch right before each expansion that changes gameplay pretty wildly across the board. There’s little point in getting up to speed on the 5.x stuff when the 6.0 patch is going to come along pretty soon and blow it all out of the water. I would keep an eye on something like mmo-champion.com or the official WoW twitter feed to get an idea for when that’s coming down the pipe.
I mean, if you really want to pick it up now, go crazy, but I would start with a class that you don’t think you’re seriously interested in just to get used to the controls and social stuff, then flip to whatever you really want to play when 6.0 comes along.
Hope that helps!