I like the gameplay a lot! The many different types of platforms made for a lot of variety, and the faces on them were a great touch! Plus the story is fun, and the characters look like Marty and Doc from back to the future, which is fun too.
I had this problem where the main level music had this horrible spike in it. 
I don't know what program you used to create the music, but man, I hope you can fix it.