Not bad, but still.
It's not BAD bad, but it's not good yet. I approve of you submitting it to Newgrounds to get feedback and such. It'll probably help to see what your audience thinks.
1) Try and get less annoying background music,
2) Mario's kinda floaty.
3) You should make killable enemies.
4) Also, just try and refine it to make it as nice as you can, mmkah?