I felt that the leveling content was pretty refreshing from the TBC and vanilla stuff. It was much more diverse, and storylines were much better interwoven with the questing content. Questing has improved a LOT compared to vanilla and TBC, they should really overhaul that to bring it up to standard.
I lóved my trip from 70 to 80, and Northrend is a beautifull continent. But what WotLK definatly lacks is lasting appeal. The endgame really is the same ol' same ol', and there is barely any of it. Most guilds are picking their noses now, waiting for Ulduar. That's also looking up to be quite refreshing from the usual raid-style. I won't be able to actually play the instance, but it's looking pretty good.
Anyway, in short, while the road to 80 is refreshing, right now staying at 80 is really the same as usual. I enjoyed WotLK a lót for 3 months, after that I simply ran out of content, and I'm not the farmer kind of guy so I stopped playing. I have no regrets though. Some people call leveling to 80 "pointless", but that's like they're seeing it as a neccesary evil to reach some meta-game. I completely dissagree, don't forget that the majority of the content is still in the road to 80, and not in the endgame stuff. Why barely pay attention to all that, why can't you just enjoy the whole game instead of just racing towards a goal? A wise man once sad, the road towards the goal is just as important as the goal itself.