A pleasantly easy hack, but not too showy in creativity. Tileset-specific enemies are sparingly used, with only the castle really having them, and the hammer bro appearing later, but enemies don't have any strategic use. You'll see a Goomba walk into a wall of turn blocks and turn around to fall down a hole, and everything just walks on a ledge and is easy to avoid. The autoscroll rooms don't have a lot of activity; you still just jump over everything. The design's not very repetitive except in the fast-scrolling room.
In the castle, you have a P-switch race, but I'm not too fond of the setup since activating it too soon can trap you, and I was disappointed that the coins guiding to safety in the next room was a one-screen concept that didn't take it further. You're given a Yoshi in one level, and his only purpose is to be abandoned to clear a jump underneath a solid wall. It makes you wonder why these design ideas are even included if they're not utilized well - they're either too short or outright don't make sense with the design.
The custom graphics are crude, with the tree barely being recognizable as a tree, and the sand has little more detail than brown grains on a single-tone wall of tan. It feels a little weird in caves that have an all-dirt background seeing the walls not move and looking exactly the same as the foreground.
Furthermore, there are a lot of graphical nuisances, from the annoying fragment left in the score counter because it's still pointing to the top corner tile of the Koopa, to the rather obnoxious VRAM corruption that occurs after you beat the first castle. The SMB3 muncher sprites have bad palettes, and the castle has sprite tile memory issues which are guaranteed to trigger if you carry the Goomba with you. Some areas have a bad FG/BG starting position, and the first level has an area that'd make a lot more sense to use a screen-scrolling pipe.