If you are an RPG fan, or just enjoy a really good story, you owe it to yourself to play Knights of the Old Republic.
First of all, this game really makes something out of the Star Wars license. Unlike the recent films, which though enjoyable are pretty lousy, this game was produced with the highest production values. Voice acting is the best I've ever heard in a game, and you'll find yourself interacting with characters just to chat and see what they have to say. Also, there are some interesting moral concepts that are dealt with in the game, especially the idea of killing, which turns out to have a huge role in the games plot. Also, there are many references to the cyclic nature of evil. It is obvious that BioWare views its games as artistic property, and Knights of the Old Republic takes a good stab at making itself a work of art.
The game is weakest in the graphics and level design department. Most of the games levels are very small or restrictive and unrealistic, while the graphical effects are nothing special. However, this turns out to have very little impact on the actual enjoyability of the game.
The soundtrack is excellent and at times sounds good enough to be from the movies, though thankfully it's all original. All the sound effects are very well done and sound just like the should.
One important aspect of this game is the way you feel more powerful as you level up. At the beginning of the game you feel relatively weak, though by the end , you really get the feeling that your character has turned into something special. The conclusion to this game is as epic as they come, though there are some cheap tactics you can use in the final battle.
Overall, this game is the best use of Star Wars license EVER, including the movies. It is one you will remember for a long time, and has already become an RPG classic.