I played WoW for 3 years and can honestly say that it was the best game i ever played, but if i were you i would wait 1,5 month before the next expansion so you reach lvl 70 in time for the next expansion.

Pros:
1. Smooth Gameplay
2. Population
3. Raids
4. Arena PVP
5. Community
6. Wrath of the Lich King is coming soon

Cons:
1. The Burning Crusade
2. Wrath of the Lich king (new expansion) is coming soon, which means that
when you reach lvl 70 there's nothing to do that lasts for the next exp.
3. Leveling shouldn't be in the game, as it's just a pain in the ass to reach the actual game (end-game).