I finally played this today, and here are my thoughts!
Amazing
1) Echoing what's been said already, just overall, great job!! This is already one of my favorites!
2) The art design is gorgeous and the map is gigantic
3) The ramps are super fun, well done
4) The tiered-style pathways are creative and clever; this level kind of feels like the Sonic equivalent of a hike that turns into a bit of mountain climbing.
5) The palm trees look great; the colors are well balanced; the badnik choices are good.
Suggests for Improvement
1) Because it's such a BIG level that you want to spend a lot of time playing to explore, the first thing I would recommend changing is the music track. I know there are some great Palmtree Panic remixes out there that are both longer and better suited to "Neo" than the original track.
The Sonic CD soundtrack is great; it's just some tracks like PP are little played out, imo, like GHZ or Chemical Plant. After 7 minutes and however many times the track looped at that, I had to decide either to turn off the music or stop playing the level because it was becoming annoying instead of enjoyable.
2) There's a lot of sucker-punching crabs! I'd replace 50% of them with an equivalent badnik without a punch (is there coding for the Crustachean with punch :off:? Like a blue crawla version of Crustachean?) Another way to balance would be to double/triple the amount of individual rings floating around. But I'd rather just have fewer punches thrown at me.
3) It's sometimes a bit unclear where to go next, and I found myself getting turned around quite a bit... this is part of the challenge of SRB2 map making in general, it seems, bc it's often an issue for me on first-playthroughs (and I think most ppl) for practically every level with wide open level design based around tiered platforming to progress. I'm not sure of the answer, exactly, because I can tell you obviously put thought into this already; it's clear in the design based on the usual things like rings and star posts, and paved pathway. And adding arrow signs is not ideal, nor do I think it really needs it.
(3a) I wonder if designing the course could subtly suggest direction with platforms being guided visually... maybe change some existing platforms to be floating (permanent floating) and removing some more of the walls/mountains to guide the eye in the right direction a bit more?
(3b) Some of the pathways that seemed to lead to closed spaces ... maybe could have more ways to connect back to other paths without backtracking? (There probably already are ways that I'm not yet seeing) For example maybe an underground tunnel that takes you in ball form to another part of the level to pop up back (kinda like the tunnels in Egg Rock, but underground, like in GHZ or the tubes in ChemPlant)
4) Smallest thing, not sure if it can be improved because of the size (also i'm 2.2.0 mac), but there is some noticeable framerate/slowdown, for some reason usually near the waterfalls I noticed.