I'm playing Mass Effect almost obsessively. It's a very good game. Definately reminds me of the first KOTOR (Knights of the Old Republic), which was also an excellent RPG.
Bioware really knows how to make characters come alive, they write an excellent story. Better than most movies I've seen. I used to joke that if only George Lucas had let Bioware write the prequel Star Wars movies, they would have been amazing!
Either way, I'm about 3/4's done with my paragon combat specialist, and I've just started and Evil (being evil is always more fun!) Adept, so we'll see how it goes. I'm having a lot of fun with it!