Looks rubbish to begin with because of the graphics, but it's actually very fun. I got all of the upgrades, but then killed all my groupies :(
You could make it better by adding in-game acheivements such as "Jump 600 metres distance" or "Do two flips in one jump" etc. You could also add different levels, for example with bigger hills or more than one hill. More tricks would be good two.
I hope to see a sequel!!