Very Good! Lots of potential
I beat the game in 12:41 and it was quite fun but the graphics left a lot to be desired. Themed levels would add a lot to the game i think, a sound for when the bike crashed and perhaps when the guy hurt himself (also I think the game would do a bit better with more violence, some innate human enjoyment out of seeing someone get injured) and maybe add more detail on the terrain (its dirt biking where's the dirt).
Overall though, well done! You kept me entertained for 13 minutes.