Hey there! I just reviewed your level and here's what I think:
- There were so many fire flowers at the beginning. Two would've been more than enough, considering the fact that you're providing 2 Yoshis as well.
- Is there really any need for the initial message? Most players would be curious to see what's buried, especially if it's at the very beginning of the level.
- I personally wouldn't recommend placing several enemies close to your starting position. It's not that they were difficult to kill but it can catch some players off guard a bit.
- Is the player not intended to go through the same door again (from section 2 to section 1) as the door background was there?
- When I beat Birdo at the end, nothing happened. I tried seeing if there was a hidden block or something but alas, I had to kill myself. How's the level supposed to end?
- The whole level felt a bit short to me. That in itself is not bad but I didn't feel like there was much of a challenge to it, really. Perhaps add some puzzles or more platforming options?
- Music seemed to fit each section and there's nothing wrong with using non-custom tracks.
- The level background felt a bit bland and I don't recall seeing any coins or coin blocks. Perhaps make the scenery feel a bit more natural and less 'blocky'? And maybe make the airship go up and down or add a propeller to its back?
- When I was falling down the pipe in the last section, at first I thought the black background was a cut-off error and only then realised it was used as the sail for the airship (which I thought was quite clever).
Overall, the level feels like it's missing something. It's not bad per se but I would recommend adding some challenges, getting rid of the unnecessary 2 power-ups at the beginning and reviewing the ending (see comment above). I would give this level a rating of 4/10.