Great work! I've said it before, you really have a knack for set design: Your rooms are big and populated with scenery and geometry that hold the players attention and compels them to explore. First playthrough took me 7 minutes, pretty good for a 2 minute map. It's pretty. I hate hate hate the music since it's exactly the sort of shit mom blasts when she's roleplaying with her faux Native American shaman friends on Facebook, but that's a personal issue.
The problem is that you're not really rewarding the player for exploring. There's only one brief path split at the start of the level. You've got tons of nooks that
look like they lead to something interesting, but only amount to eye candy or a dead end distraction (like
this). I thought the map was designed with Tails or Knuckles in mind since you had all these goodies on pillars that Sonic couldn't reach, but then playing as them just made it clear how much of the map was empty space. It's not much fun either- for your next map, I want you to focus on building something challenging without relying on instant death traps. You need more gimmicks. Figure out how polyobjects work and start playing with moving platforms. As an aside, which of the stock single player maps is your favorite, and why?
Map also needs some serious cleanup. Merge your thok barrier with the play area, Don't allow
spaces like these to exist. If the player doesn't have a reason to be up there on the edges of the map, trim them out with single-sided linedefs. It's just more work for the renderer at best, and it enables Knuckles to skip sections of the map entirely at worst. Start using the noclimb flag so players aren't cheating your layout or wasting their time climbing everywhere looking for secrets. Giving you the business here since you could definitely be one of the community's greats if you can just pair your artistic sensibilities with solid game design.