The speed you move is so fast that the small gaps between land can be walked right over. The jump is set to a set amount and isn't based on how long you're pressing the jump key, which makes it very tough to coordinate movement. Additionally, if you fall off, you aren't reset back to the start and are stuck off screen forever.
Aside from these gameplay elements, the music and sound effects are WAY too loud. An option to lower them or turn them off would be nice.