In Detail...
The first section takes place in the sky and the tileset used is the SMB3 wood block stuff (not the wood overworld tileset, the block-1 derivatives). The platforms are connected by those SMB3 airship screws. It looks weird, and if it's supposed to be a level without custom GFX, maybe making the platform hang on the air with those theatre ropes would look better.
We already start with lots of platforms. We stand on a platform with no one else, but above our platform is another one with a red Koopa and a ? block. But first we must walk through three airborn blocks and land on another platform, also with a red Koopa. Along the way we collect three coins. There's a pipe between to platforms, with a Piranha Plant inside. We then reach two parallel block-1 walls with ? blocks. One has a coin and the other has a Super Mushroom. Then there's a moving platform above a bottomless pit and below two block-1s with some coins around. This moving platform is between the block-1 walls and a blue SMB3 sizable with a red Koopa on top. The SMB3 sizable is airborne and is just a bonus area, since it leads nowhere and has just the Koopa, a brick with coins inside and an invisible ? block above the brick with an 1up.
Jumping to the two block-1s is where the level advances. We go left to the platforms that were above us before. There's some red Koopas along the way until we go back to the platform above the first platform. There's a block with a piranha vine inside that you should climb. We go further up to more platforms with Parakoopas, Koopas and Goombas. Along the way we also encounter ? blocks (one has a Fire Flower), pipes with Piranha Plants and, finally, a moving platform path. The moving platform path is small, and because of that it's hard to put enemies without seeming like there's too much or too less (here it's too less).
After the moving platform there's a nice looking mountain of sorts made of block-1 derivatives and SMB3 colored sizables. It's a mini mountain you climb down, with Goombas, Koopas and a Super Leaf to collect. We then pass a moving platform and more airborn platforms with lots of red Koopas and the occasional green Koopas and Goombas. We then go down a falling platform that lands on a line to move like an actual moving platform. There's red Parakoopas along the way. After this moving platform there's a few more platforms with Koopas and Goombas, and then a pipe that leads to an overworld area with a SMB3 exit.
In General...
This level is really short, but very fun. The lack of custom GFX doesn't stop the level from looking nice and clean (except for the airship screws, they annoyed me a bit). But the level lacks enemy variety. There's a lot of red Koopas walking around, some red Parakoopas and few green Koopas and Goombas. It feels like Blank knew he had to put an NPC there but didn't know which one so he placed a red Koopa whenever he didn't decide it. This may be a nitpicky observation, but still.
Overall Rating: 5/10 stars - Approved!
Not a bad level, but it's not something special. It won't make you come back constantly, but it will give you some fun. I may have given an average rating, but I still recommend this level for those who want a fun throwback to the good old SMB3 (which i actually played!), because the detailed overview I wrote above doesn't do it justice.