Very good game, easy to control the ATV, and better trick animation.
Customization (e.g. ATV customization, player customization, etc.)
Better controls - Easier to move, easy to land tricks on jumps, etc.
Great graphics
Great animation
Mini-games are sweet
And the list goes on...
Although there are many flaws as well:
Too repetitive: "I won a race! Cool, I can buy the Fury bike!"
Too easy: Computer - controlled players are too easy to beat.
Takes a long time to learn the controls, since there is so many. I still forget which button does Scorpion!
Addictive... A little TOO addictive...
And the list goes on...(again)