KOTOR2 is a game with a much darker and depressing, almost gothic game setting which leaves a lot of questions unanswered. KOTOR1 was a cookie colored pretty much hyper game that finished its storyline and only left hints to how the story might continue in case Lucas Arts decides to produce a sequel.
What I am trying to say is, it all comes down to personal preference really. I personally liked KOTOR1 better too, nothing beats Bioware when it comes to telling stories and it's a shame they decided only to produce titles for the X-Box anymore. However, KOTOR2 is great and fun too, just in a different way. The worst thing you can do really is to compare it to its prequel even if that'd be a logical thing to do.
My $0.02.
