I have to say, I was actually very pleasantly surprised by this level!
The first thing that I noticed was how open and empty the level felt, without too much decoration to fill up the space and make the level feel alive, but that's really my only major complaint.
I really enjoyed the core gameplay, there were a bunch of unique little platforming segments that really mixed it up and made the level feel varied and fun to play, like the laser factory segments or the rising lava areas.
I also especially loved the usage of different environments, especially in the second act, going from inside different parts of the volcano, going outside, and exploring the lab, and especially the varied texturing used in the volcano segments kept the level fresh and alive.
The split path with the two forests roads and big gray cliff was a refreshing way to incorporate upper and lower routes and the Spirals cliff were fun to run around. They had the air bobbing effect applied to them though, so if you moved too slowly, the platform would lower and you'd bump into the wall of the next one instead of clipping onto the top of it.
I'd suggest try playing with bigger platforms next time, Sonic & Co. are all pretty quick, and having more room to navigate doesn't necessarily mean that the platforming is easier; it usually just makes it less frustrating. For each act, try working with similar colors, I saw a few blue CLIFF textures in the Act 2, and it really clashed with the theme you were going for.
Lastly, always remember to check the Float box for your rings, you can do this easily to all of them with the Find and Replace Mode.