Ok I admit I am a huge Star Wars nerd. I am also a fan of MMO's. I actually started the MMO thing with Star Wars Galaxies. Originally created by Sony, it had some good points...but mostly lacked any kind of story. Also because they tried to create it during a specific timeline in the Star Wars universe it severely hampered the story and the use of Jedi's. Still it was my original crack. Eventually it got stale and was time to move on....
After that I switched to Everquest II (Obviously not Star Wars Based), while the story was better than SWG it was impossible to level and perks were meh. Played that for awhile until I started what I believe will be the greatest MMO and what all other MMO's will constantly be compared against. (much like the vaunted bama defense of 92). World of Warcraft...it had everything story line, leveling wasn't a challenge, and you were constantly getting new perks. I loved it played it religiously almost every night for 2 years. Had multiple high level characters. Made RL friends through the damn game. As most things though it came to an end, I started to grow weary of the grinding, and to be honest the constant playing started to take effect outside of the game world (ie lack of sleep) so I decided to quit and I haven't played an MMO since. Roughly 3 years.
Enter Star Wars the Old Republic....holyee shit I am addicted again. Just downloaded last week, the new creation team of Bioware and EA, have created an alternate Star Wars universe in which I am sucked into again. While my overall impression is that it is not better than WoW, it is something that can be built upon immensely. If you are into MMO's I highly recommend giving it a look and if you are a Star Wars freak like me it is a must. The story line is amazing and the gameplay is flawless, granted the game is new (released late December) but I have had zero lag issues while playing. The game actually plays as if you were playing by yourself with cutaway scenes that feature gorgeous content and story lines.
http://www.swtor.com/