Overall the level was okay. It has a good athmosphere and I liked the block tileset. I did find a couple of problems.
The berries are in the foreground and do look strange when you stand "behind" them. You did not have to place it in the foreground.
I did find a couple of coins that clipped through the ground. Make sure when you make slopes, try disabling auto-align for more precision coin placement.
You did a good job on the BGOs in the first section, but the sky section was too empty.
With the NPCs you did a really good job with the chomps. They were all plaaced in a fair way.
The biggest problem with the level were the spinies. I liked the gimmick of how the fighter fly popped some of the bubbles, but the spinies are too tough. The level was spammed with these in the first section, and if they were replaced with a easier enemy it would have been fine. The spinies were a bit better placed in the sky section, except one part. I did see the hidden hammer suit secret in the beggining, but you should not rely on the secrets to justify the level's difficulty. There was also another hammer suit after the checkpoint, which I feel was too overpowered.The level was'nt too difficult even with all the spinies, but did get a bit annoying after a while. The secrets were placed correctly. I also liked what you did at the end
You did do a good job, once I found the hammer suit the level was really fun to play.