This is a very interesting and solid level.
Secrets, although easy, were interesting to find.
Level Design needs to be improved a little. Feels a little square, and also a little flat, it is worth playing a little with the height of the floor and ceiling. I also advise you to practice more with slopes, the level will look more beauty, and thus you can make more interesting obstacles.
You can also make the paths a little more varied and for different characters (like Knuckles, Amy, even Fang yeah).
Сustom (or at least rarely used) textures would be more suitable for your future levels. (Seriously, it's not very nice to see GFZ textures again, even at such a solid level.)
I hope that you will see this and work on your mistakes, with patience and interest, a cool level pack can come out. I see that you already have enough experience in mapping, so I'm sure that you will succeed!