This hack feels like it could be a Super Mario World: The Lost Levels candidate. The theming and designs seem like what you would see out of such a game. While mostly traditional, there are a few puzzles and awesome but well-hidden bonuses. The lengths of the levels though are like something out of a Kirby game: with the exception of the ghost house, they're LONG. Yoshi doesn't get utilized well in the level he's in but can be an amazing asset in the level he's usable in after the fact and some parts warrant the cape to get through, which is unusual because of the stigma around these two features as being "overpowered" and "should be saved for later." This hack may last you over a half hour despite being only six levels long.
Visually, this hack doesn't really use non-vanilla palettes, but it does look very clean. The only mess to speak of is the "end of the demo" where you get cutoff and block words to jokingly piss you off after a satisfying experience. I don't have sprite tile memory problems, which is great.
This hack's difficulty is very borderline: it's hard to tell if this should be normal or hard. Some timing in the castle with the falling platforms and Podoboos is particularly brutal and I can't quite seem to safely dodge one of them and weighed with the average length of the levels with no midway points, I decided to label this hack Hard rather than Normal.
ASM use is minimal: there are the breakable bricks featured in SMB1 and SMB3, but that is it.
There's a pipe in Green Valley #1 that has a forced hit, even though the pipe itself is optional to go into. There are a few areas in some levels where you can get permanently stuck: if you're a derf then you can get stuck in the breakable brick structure in the second level, and in 1-3, if you're not big when you reach the wall, you don't get a second chance to try to beat the level and must die. Other than these awful annoyances, this was a very fun and otherwise polished hack.