I've been playing this game since release and I can say with confidence that I am enjoying it more than WoW. A little history first, I've played WoW since before the first expac and was a pretty hardcore raider for a few years, but eventually the repetition of the game and the same overall story+quests eventually got me bored and I quit last year sometime.
Now before you go: "but wait, isn't ToR just like WoW but with lightsabers?!"
It is very similar to WoW I must say, but I do find the new character classes and worlds to be very refreshing and engaging. I also like the idea of the 'daily quest' where you go fighting in your own personal star ship and perform escorts or general destruction where needed (haha). This breaks up the normal third person combat you get with your average MMOs and injects some fast-paced (and graphically beautiful environments) into the game.
Another awesome aspect of the game is the crafting system. Rather than perform the craft of armor or the search for minerals; you are able to send off your companions (NPCs that you befriend/aquire during your questing) to do all the dirty work! Talk about streamlined! This frees you up to continue questing or performing whatever other duties you need.
I'm yet to try all the classes but I have played both the Imperial Agent and Jedi Consular (IA is ranged and JC is melee). They both bring a nice mix of new abilities that I haven't seen in WoW and some old favorites (but under a different name of course).
All in all, if you are a fan of MMOs I would highly recommend this to you, even doubly so if you enjoy sci-fi over fantasy worlds (which I do)!
I'll leave you with some screenshots I've taken while running around questing.
Feel free to ask questions!
The Jedi Homeworld
Walking towards the main Jedi Temple