I don't know, to be fair. I've played the beta, and all I could think was... Wait, who modded WoW with Star Wars themes? The mechanics are identical, the much hiped Bioware TM story is meh, and it's only real advantage over WoW is (barring the StarWars rabid fandom) the fact that it's fully voiced. WoW actually has some great quest lines if you bother to read the text.
I really didn't like the gameplay with the ranged classes (the Smuggler in particular feels like playing a Siege Tank in Starcraft: deploy, nuke, un-deploy, deploy, nuke, un-deploy, and so on) and the time I had to spend on Coruscant as a Republic character was, and I'm really not exaggerating here, some of the worst time I've had with a game in my life. And I had to do it, because I really, really wanted to enjoy ToR, and I though, fine, fine, it's horrible here, but it has to get better later, right? Well, not really. And since leveling a character is one of the things I like about MMORPGs, having to go through that again? No. Just No.
Also as a WoW player, it's just not worth picking up a full priced game and paying the same subscription for what is currently a slightly more annoying version of the game I'm playing anyway.
However I see the game is very successfully, despite the fact that I thought it wouldn't quite be. I don't know if this is just Star Wars fandom, WoW hate, a combination, or something else. All I know is that, for me, a person who enjoys this kind of game, TOR was just not fun for some very clear reasons.