I have played a Jedi Consular for about 4 hours now and have a pretty good idea of how Star Wars The Old Republic will play. I'm bound by the NDA, so can't discuss specifics, but here are a few general impressions.
1. Polished. Amazingly so. I'd heard bad things about the game from other beta testers, so I was pleasantly surprised to play a game that seemed months past release. The only problems I encountered were the initial queues when the beta went live. No server lag, no game bugs, nothing to complain about on a technical front.
2. Pretty. The art is very appealing. Somehow it captures both the cartoon feel of WoW and a more realistic style I really like. Animations are nothing special, but fun and help create the illusion of force powers and abilities.
3. Easy. There is nothing challenging about the game at all, in the early going.
4. Standard. Game structure, development, and style is pure traditional MMO fare. There is nothing new in the underbelly of the game that I encountered.
5. High quality. The quest presentation is the best I've ever seen in any MMO. Period. No comparison. You'll see why when you play.