The music doesn't loop, so after about a minute in the game, it goes silent.
I'll admit that I'm not the greatest at platformers, but I couldn't get past the jump after the second slime. There's so little space to land without dying there, and jumping on top of the slime didn't seem to help without a running start, but I couldn't manage that without dying.
It doesn't help that the character's jumps are very floaty. 'Floaty' isn't generally what you want with platformers. It just makes the game frustrating and difficult to control.