Most MMORPGs have far too narrow a definition of the term "RPG." For them, it seems like a game is an RPG just so long as it has ability scores, character levels, and boots that improve your accuracy. To me, those are just incidentals. What makes for real roleplaying is being given an opportunity to express an attitude or a principle and then watch the game world respond to it. Being a hero or villain should matter not just in terms of the missions you choose to run, but by how you choose to run them. Games tend to define characters almost exclusively in terms of mathematical values - strength, speed, accuracy, etc. - but characters in nearly every other medium are more often defined by psychology. BioWare's Star Wars: The Old Republic gives us the best of both worlds with characters who not only advance both in terms of physical ability, but also express a kind of emotional identity.
When I think about my main character in The Old Republic, I don't immediately think of him as a "tank" who's just there to soak up damage. In fact, my character's mechanical identity is pretty far down on the list of things I think about. Instead, I think of him as a Sith, totally invested in the desire to be remembered and honored for his service to the Empire long after his own death. To that end, he adopts the Roman idea of the patron-client relationship. Do what you can for people in power and trust that their influence and favor will benefit you one day. Likewise, reward those who seek out your patronage but do not hesitate to punish disloyalty.
While I may have similar notions about characters I play in other MMOs, The Old Republic is the first MMO where that attitude actually seems to matter within the context of the game. Suddenly, I'm not making choices based on the purely mechanical benefit to my character. Now I'm actually investing myself in the situations and making decisions based on my character's outlook. The sum total of those decisions creates a character biography that transcends the skills and equipment I've gained along the way. I mean, what's more meaningful: that my character has a lightsaber that boosts his strength or that he seduces (and allows himself to be seduced by) women in power? To me, that's real roleplaying and it's something that The Old Republic does better than any other MMO I've ever played. In fact, it does it better than most single-player RPGs I've played.
What makes it work is that the game offers really engaging choices in nearly every single encounter. Do you let the bad guy go in order to save a few innocent lives? Do you exploit a high-ranking member of your faction who has lost touch with reality? Do you give a defeated enemy the right to an honorable death? The decisions are reinforced by the game's frequent callbacks to your previous adventures and your companions' almost immediate reaction to what you're doing. Stand firm for the Empire and your junior officer will beam with pride. Perform a selfless act and your Twi'lek thief will shake her head in disgust. While there is some resetting for the sake of preserving other players' experiences, The Old Republic makes you feel like your decisions really matter.
The situation becomes even more appealing once you add in other players who have the opportunity to take your interactions with other NPCs into territories you didn't expect. In fact, sharing conversations with other players makes the game feel even more dynamic and relevant. Imagine you've just fought your way onto the bridge of a starship and confronted an enemy admiral. You'd like to spare his life, but your bounty hunter friend decides to kill him anyway. What's especially cool is that each player gets to choose the response they'd like to make at that crucial moment. Those who choose the merciful option gain Light Side points, even if the player who finally gets to make the call ends up killing the guy.
The combat is fantastic, not just in terms of the exciting visuals, but also in terms of the choices you get to make. These characters really look like they're connecting with each other with every lightsaber swipe and every blaster shot. There's a strong kinetic element to the battles here so, when a bounty hunter launches a rocket strike, you really feel the weight of it in the way the characters respond. It's too bad, then, that you miss a lot of the combat just watching abilities cycle in your hot bar. I'm willing to overlook a bit of bar-watching, because it's sort of standard with most MMOs, but it's a shame that BioWare made such great animations for game that demands so much of your attention elsewhere.