Great level you have here. The length is perfect, the graphics are fantastic, and the music works well. (However it is a bit awkward that theres a short second of silence before the song starts.)
Just some things I wanted to point out.
So theres a bonus room down this pipe which is located just before the midpoint.
Instead of coming down from the pipe, Mario comes up out of thin air.
A simple fix.
This may be a bit more personal, but I'll bring it up anyway. When you come out of the pipe, you are past the midpoint, and even if you know it's there, there's still a tricky jump that needs to be passed. I suggest moving the exit to this pipe before or closer to the midpoint.
How do I make these jumps? I assume the second one can be made using the Racoon Leaf in the level, but to get that I need to make the first jump. The first jump I keep missing by a pixel. I'd suggest making them a bit easier, or maybe I'm just missing something.
Anyherp, great work!