To the original poster,
It depends what you define as "a lot".
If you only play through the game one way you will inevitably miss some things, especially given that certain NPCs are only joinable depending on gender and alignment. So already that's something that you missed.
Plus there are slight variations in what happens (some say not even noticeable, however) depending if you choose a lightside or darkside way to solve quests.
IMO, there's enough content (even with the rushed ending, and the cut content) there to provide enough new things to discover if you play it at least one or two more times. I played both KOTORs about 4 or 5 times each, and at that point got pretty much all I could out of them.