Played through it. Here are my thoughts:
-you should really look up some tutorials on pixel art. This level would've been much more playable if it used vanilla graphics because...
-the spikes look like decoration and the pointy part is almost invisible. All my deaths come from not noticing the spikes.
-the level lasts for like 20 seconds. When you get to the end the song starts to pick up. I found this a bit disappointing, because the premise of jumping across bubbles could've been carried much further than this
-the song doesn't fit at all
-it's easy to get stuck in the last section if you mess up the goomba jumps. Granted, this level can be completed in 20 seconds so it's not a huge setback, but being able to respawn them in one way or another to give the player an opportunity to learn would be fair.
-I thought the stars were harmful until I jumped on them. Note block would've been my last thought.
-None of the enemies pose any kind of challenge, aside from the bubbles at the end which I mentioned before. In fact, there is a parakoopa at the end of section 2 which just dies. That's it. Good enemy placement and variety (not).
Verdict:
Watch this/10