Answer:
In many aspects it is better, it takes full advantage of modern Directx10 capable graphics cards.
It demands more PC resources but given that it was released about 4 years ago almost any new PC is able to run flight simulator x aka FSX.
This Wikipedia article has covered all the new features:
http://en.wikipedia.org/wiki/Microsoft_Flight_Simulator_X#New_features
I highly recommend the move to Flight Simulator X