Good but many complaints.
First off, the controls and sidescrolling are absolutely fluent, but what's up with the invisible walls? And also, why is it that when I run into certain walls I lose health? That doesn't make sense.
The music is nice but way too short, and also, why are there no sound effects? Shouldn't I be hearing "Cling" noises when Sonic runs into the coins?
Last but not least, everything's too small. There should be a bigger close up on every thing, you know, like a classic sidescroller. Everything's too small and you can see everything. But that's just my pet peeve.
Other than that, everything's fine and dandy. Just gotta fix those few flaw's and you're good to go, if you're a first timer on this, bravo you have my applaud. Keep it up.