Some great new aspects to the game. But there are some serious issues with how this expansion has changed WoW.
However, leveling now is a walk in the park! Even at the higher levels the difficulty of the quests are extremely easy. While leveling my main UD rogue I was surprised at how easy the new content was. On top of that, almost all the quests were solo with the exception of some instant quests and a ring of blood style quest in the Twilight Highlands. Another bad aspect in my opinion is the confusion with the Warcraft lore. I don't know if its just me but things kind of stopped making sense once Sunwell came out! Cataclysm seems to make things even worst. (Ex. UD Hunter & Tauren Paladin....Huh?)
I also found the highest level of glitches I have ever experienced from a Blizzard game. The worst one was in the Worgon starting area during the region's final quest. Four other players and I were stuck in a phase running around for about 15 minutes trying to figure out what to do. We finally had to refresh the quest and run all the way back to the quest giver. This was a pretty major glitch for blizzard standards!
Overall, decent expansion, decent additional content, but by far the worst of the three expansions.