As was said before, pick up the trial and give it a whirl. Level several classes up to 20, both Horde and Alliance, and get a feel for the crafting. The game is solid and very enjoyable. That said it has a pretty bad case of the pricks so be mindful of that when you ask questions. Also to keep in mind if you decide to purchase all the expansions you will be paying roughly $100 so it isn't the cheapest thing to dive into. Although since the orginal game comes with Burning Crusades now you could hold off on getting the other two expansions until you get up there. You will just be unable to play as a death knight, goblin, or worgen. Not sure if you could get archeology (probably not).
Good luck with your decision and have fun. :)