I have never felt more a part of the Star Wars universe than when I'm playing KOTOR. You jump right into the game and the story and it doesn't let up. There are so many sidequest and NPC's to meet hours pass by quickly.
At first I was a little dissapointed with the control of the character...I kept wanted to control each swing or shot and jump around (too many hours of Baldur's Gate), but now that I've got several characters to play and I get to coordinate all their actions I've forgotten any gripes I had at first.
The graphics are extremely good for a game with so many different levels and character types.
There must be thousands of lines of dialogue throughout the game, nearly called it a movie there, and the firing of blasters and the "woom" of a lightsaber are perfect.
One thing I've noticed is that everyone has enjoyed just sitting around watching me play the game, giving pointers and asking me to try different things. Its an entertaining game just to watch and I think the pace of the story and action is what keeps everyone interested.