This is the only Star Wars game I liked since Dark Forces 1&2. The story pulled me in - especially when talking to the other characters on the Ebon Hawk and learning about their pasts. The characters themselves were diversified and dynamic (mostly). Sure Canderous is always ruthless and Carth always whines like a baby, but Jolee made a good "father" figure, and Mission made a great kid, though I didn't use her after I got into the Vulkar Base. They had emotions and lives that went on outside of the storyline, and gave the universe a little more reality.
The story was good, though pretty predictable, and straightforward.
The last Star Wars game I played before that was Jedi Starfighter, and that game was really bad. Gameplay, controls, story, everything bad.
But for KOTOR I'll go with best Star Wars game - it was fun and kept me, a casual gamer, addicted.