I'd say no. You'd be joining fairly late in the game. You'd have to buy the game and two expansions, but you'd hardly get your money's worth on the original game and the first expansion. Also, the second expansion is pretty far along, so you'd be hard pressed to catch up there as well. If you really want to, buy just the vanilla WoW and try it out. If you hit level 60 and still like it, get Burning Crusade and if you still like it at 70, get Wrath of the Lich King.
However, I'd suggest trying a different MMO. There are a fair few coming out that might turn out to be better than WoW, or at least more innovative. Also, if you haven't tried any MMOs yet, maybe you could try one of the free ones to test the waters before you financially commit. Personally, I'd reccomend Dungeons & Dragons Online. It's going free in a couple of weeks.
However, I'd suggest trying a different MMO. There are a fair few coming out that might turn out to be better than WoW, or at least more innovative. Also, if you haven't tried any MMOs yet, maybe you could try one of the free ones to test the waters before you financially commit. Personally, I'd reccomend Dungeons & Dragons Online. It's going free in a couple of weeks.