The design is good. It kinda recalls SMW for how it's handled: very player friendly and easy, which really fits a world 1. Maybe sometimes it can result a bit too flat, but, again, most of this is because it's a first world from my point. Yet, there's not much variety in this hack. The author mostly uses commom enemies, for example, koopas and goombas. It still manages to be fun, the levels themselves aren't totally flat, so I guess it's okay. Last but not least, levels also don't last too much, they don't take much to complete, and this is a small minus.
The aesthetics are good as well. Some palettes were questionable, since the author coloured the outlines too, which are always black in most of the levels. Overall, this hack looks good though, maybe I'd have used more decorations.