GTA: SA is basically identical to the PS2 version except for the better graphics on the XB. As far as better load...
Bugs found in the original PS2 version are still intact on the XB. I have lost several games to dirty disc errors as well. It may be that my XB is getting pretty old, so beware all first generation XB owners.
My biggest gripe against the game is the control lay-out. it did not adapt well to the XB controller for flight or vehicle drive-bys. You have to use the black and white buttons to aim out the right or left of a car while pressing the "A" button to fire; very clunky. The black and white buttons are also used as rudder controls for flight, but that was not as bad, just takes a bit to get used to.
If you don't own a PS2 then don't miss out on this game. If you own a PS2 and XB, stick to the PS2 version for better controls.