Most of the levels in this hack are nice, though not very memorable. Among the best would be Bowser's Castle, which has a lot of star craziness and a straightforward item chain trick that avoids all the tedium of babysitting. The beginning of it is rough, though, with thin slope platforms above hot lava. The final level, Snowshine Mini Isle, had a lot of content, but damned be you if your Yoshi eats that green berry.
The ghost house is a level that I saw as decent, but full of so much more potential that was wasted in the 1up area during the autoscroll segment. I think that if there were more traps to turn the 1up back and you had to focus on keeping that path open while not dying to the traps in your own running space, that would have been so much more eventful than just waiting to the last second to unveil the item.
Sunshine Isle 4, on the other hand, is a level that shouldn't exist, or at least not exist in the autoscroll format. It drags down the whole hack because it's got these long empty stretches that make you want to fast-forward, and an enemy or two every 10 seconds or so. It's very boring, and I found myself dying a lot because I was too impatient to stand through the stretches of emptiness.
Sunshine Isle 2 has a bad background palette and some cutoff pipes, Bowser's Castle has issues with graphical glitching near the Thwomps, and Snowshine Mini Isle has multiple problems: the flying block platform can push you through the ground and kill you, a bush is hanging off of a slope, and you can get stuck in the wall near the keyhole. Beta testing for this hack should've been more thorough.