Perfect. Simply perfect.
You start out as a nobody and during a attack on your ship at the begining of the game, you abandon it and end up on a planet called Taris, a sprawling metropolis. After enjoying many hours on Taris you escape and go to Dantooine. Here you are made a Jedi and from there are given the main quest. You must travel to worlds like Maanan, Tatooine, Korriban, Dantooine, etc. in order to complete your quests. The game is completely open-ended allowing you to travel to any of the planets anytime you fell like it. You can choose to be good or evil too, which allows for a lot of replay value since you get different dialogue options and also a different ending.
Very intuitive combat system thats very easy to learn as well as fun. You can pause at anytime during combat to issue out orders.
Possibly the best RPG ever created, sequel was just as good, and i cant wait for the third to come out.