KOTOR 2's storyline while incomplete had so much more potential in it. It was like Empire compared to A New Hope. Those who wanted nice wrapped up stories were miserable and hated Empire when it came out. I know I did (but I was 7 so it's understandable). And perhaps it was K2's open ended, unfinished qualities that drew me in, left me wanting more, so I replayed it and replayed it. It will never satisfy, and even if it had been given time to be completed, it would still be open ended and feeling "unfinished" because it is the middle chapter in a trilogy. My only hope is that one day, the last chapter will be told and told well.
That being said, the game is buggy as all hell and frustrating. I got stuck in a bug on Nar Shaddaa my first time through and had to completely start over after over 40 hours of game play(I went and finished all the other planets first thinking I just missed something). I enjoyed the bugs, though, that let you level infinitely on the Hississ and allowed you to duplicate crystals and completely trick our your lightsabers.
KOTOR was a much better game technically, but I got the story and moved on. It didn't make me think, it didn't make me ponder the nature of the force and it didn't make me want to strangle someone for not finishing some of the romantic options. (Though Carth's declaration of love in the middle of the party was pretty lame and disappointing).