WHY DID YOU USE A FIFTEEN MINUTE SONG FOR A SINGLE-SCREEN SECTION??? ALL THAT DOES IS NEEDLESSLY BOG DOWN THE DOWNLOAD!
Anyway, my review:
This level is just kinda meh. While it is uncommon for the Player Start Location to be placed in the middle of the section, this was obviously unintentional since the checkpoint is only one screen away and Player 2's Start Location is at the far left. When testing your levels, you shouldn't move the Player Start Location from where you want it to be in the final version. Aside from a few Hammer Bros, there isn't much here for NPC variety, and the "secret" star is practically in the player's way (there's no way to fail the red coin mission, either, unless the player chooses not to do it for some reason). The hint for the key-keyhole exit is kinda clever, though, and the brief area with the Venus Fire Traps was decent, although optional. Also, since the top of the spring sprite-swap in section 2 is touching blocks, it slowly falls down. To fix this, simply move the wall that's above it one unit to the left. Oh, and the berries can be killed by shells and a tail spin, and they become Mega Moles when they die. Try using the berries from here:
http://www.smwcentral.net/?p=viewthread&t=72481
Summary:
GOOD:
-Graphics aren't terrible.
-Music fits the level well.
-Block placement is okay.
BAD:
-Level is short.
-Low NPC variety.
-Pointless "secret" star.
In conclusion: meh. If you want to have secrets in your level, much less secrets that are in the player's way, you should at least make the player work for it. Also, the level is fairly average. I'd say this deserves a 5/10.