I haven't even commented yet, as I was capturing the screen of my Gamepad, so a new version would give me a reason to play again and then comment...I guess you guys you will just have to comment again on it when I fix it. I might be able to lower the ice stage a few blocks to get more room at the top, and I can definitely change up the p switch dispensers. I can also add a more leeway to the wiggler section. My only problem that I don't really have a solution for is the boss at the end of the plant world can spawn incorrectly sometimes and it looks really bad, but that's because of how Mario Maker handles enemies off the main screen. But that is more of an aesthetics issue rather than a gameplay issue. Did you want anything look at Double before I make a revision?
Also these 30 min long youtube videos, all spent on that darn ice level, lol.
Sound good, an occasional bad looking boss spawn won't break your level!