As far as i am, i know these things:
The vision range is small and reminds me of the Game gear.
Enemies appear at your face anytime (combined with the upper one).
Springs in act 1 boss in Spring Stadium are kinda annoying.
Diamond Dust bosses (both):
Eggrobo Gamma shoots in your face when descending a very small height.
Found no way to not die because of Eggman´s "charge".
Sonic 2 bonus,no need to explain as we know that bonus is cancer.
Every other thing is fine,so far.