Sequel to one of the greatest games ever created
RCT2 had somehow lost some stuff but gained other stuff. It was instantly noticeable. Added to the game was guests being named automatically, new rides, new paths, new entertainers, brand new challenges, themed parks. The biggest thing probably was the ability to build on top of stuff, rather than ground level building - and the ride editor was definitely a plus.
However the game seemed to become either less fun or shorter than RCT1. It had lost a major zing to it. The really challenging parks were all of a sudden plugged right to the start of the game.