Not bad, this was fun to play. The design is more or less good, sometimes it's a bit too linear maybe. It's a traditional-like hack, without being too complex overall. There are, though, some tricky spots, like the fact that you need to play a level fully to get a yoshi and keep going on your journey. While I took a bit to figure how to proceed, I don't complain it much. Maybe the author could've made it a bit more intuitive. Good design overall anyways.
Aesthetics could've find some work. Some levels are a bit empty, because of the lack of decorations; some palettes also feel a bit out of palace. Not much more to say here.
As only issue worth of mention, the level "Bowser's Battleship" suffers huge slowdown, especially in the dark room part.