This stuff is really crisp-looking for having been downported to SNES. The forest with the trees is probably most impressive in how much quality the trees and bushes retain, and the trees still absolutely look 3D. I assume a background is still coming for the castle, yes? The overworld water is pretty and I love the tropical portion of the map especially! Every subsection has a ton of levels - do you have a lot of these pre-planned or are you doing improv level design to hopefully fill each dot?

The only things that look off to me are the upside-down slopes in the cave (the narrowness of the surface and the very dark lines seem out of place connecting to the other tiles, but if this is how the rip originally presented itself, then I understand) and the color depth of the Koopa house took a big hit, but it's not necessarily bad-looking. On the overworld, there's a tree in the lower left that's half on land, half over water. I found it humorous when I noticed it, but I don't know if you intend to tweak the land or remove the tree.