The level pack itself on its own does have nice ideas, but the general level design I'd say isn't put to play the best here.
One thing I could probably recommend is maybe adding more of those springs from the second Special Stage that take you between platforms into the 2D sections and stages. Generally, I feel like it's a really fun idea, is executed pretty well, and gives me a whole lot of VB Wario Land vibes.
As for some of the actual levels themselves, well, they're at least a good start. They're not great, but they certainly are still good. Most of the time the first act of Springy Hills is almost the same all around; I would probably change it to be more like a regular Classic Sonic level that also takes note of SRB2's different physics. The second act does not last all that long, which is its main losing point. I'd also probably make the terrain in general fit with each of the levels' themes; in the case of Springy Hills, probably more natural, and so on.
Overall, it's a decent experience, but in its current state I'd probably wish for it to be better.
