For a first game, the sound design and graphics are not terrible.
However, I do think that there are some areas which are just crowded with WAY too many enemies, and damage is unavoidable.
I also don't like how the jump height is always the same.
I personally like plattformers like Mario, where you can adjust your jump height, by holding the button longer, but that's just my opinion.
Also, the music didn't start when I launched the game first time, but it ROCKS!!
We all gotta start somewhere.