Too difficult
It was fun for a while but when the levels got very long and excrutiatingly difficult it is so annoying to make the lsightest mistake and to go back all the way to the start. If you make another game I would suggest making check points, so you don't lose all of your progress in a level. Also, the area where you have to jump with just one pixel on the ground was very annoying because it is too easy to be one pixel behind and die, or to go one pixel farther and fall and die.