When I got WOTLK last year I had 3 70s just waiting to be leveled. I started with my Tauren Warrior, and loved Northrend. The graphics are beautiful, the music is incredible, lots of fun new quests, etc.
When I got to 80, though, I discovered there isn't as much to do for a guy like me who doesn't raid as there was in BC. I got bored leveling my Undead Priest around 73 and let my account lapse.
Things are definitely easier in this expansion, there isn't as much to craft and it's easier to level your professions. The new PVP areas are fun, but I can only do PVP for so long, and dailies are really spread out all over the place.
When the latest patch comes out it will include the ability to dual spec, which is cool on the surface, but IMO cheapens the game. Oh well, it's probably a good thing I'm getting bored with it, I need to quit it eventually anyway!
Oh, and I created a DK, named him Kellanved, but didn't level him very far.