As I said before, your level looks pretty much and that's the thing you should be proud of, although it's considerately simple.
I didn't get some of the sublevels being cave because your level is pretty much in the sky, although they're connected with pipes and these pipes can be long. Although it doesn't mean much, I would make them sky except with lot of clouds above, pretty much simulating walls, ceilings and foreground and a slight different palette so it looks different from the main level. Of course it's up to you.
Another thing I'd suggest is adding another enemy to the level, since currently it's pretty much made of fuzzy only. For example, some pokeys or superkoopa. Without them standing out, of course. The fuzzies should still be the main attraction of the level.
Now watching in the idea, I think there's some things that you may want to fix otherwise these can affect the player experience negatively:
- at 0:58 when you get to cave, you must use the throw blocks to get the vine. However, you only have two throw blocks available and it isn't that trivial to understand what you do with them and much less to hit the question block containing the vine. I'd place four in there instead, to both give the player enough chances and make it fairly challenging to get the yoshi coin at first try.
- the pipe in 2:00 looks a bit too hard to get without dying or getting hit. Maybe you should lower it by one more block or exchanging it with one of the red pipes (of course you would move the coin and make the pipe exchanged blue and vice-versa).
Oh and, why not adding a custom music to your level?
-- it can change your level atmosphere for better. You could insert for example another mario level athletic theme or even some unsampled touhou song, as long it sounds athletic of course (though touhou doesn't have much skyish levels.... eeehh forget touhou i guess haha).
Either way, I think it's pretty good so good job!