You did in fact describe it. :-D
I guess the lack of depth is troubling. 16-bit Sonic is excellent in sound, speed, and for the platforming genre. S&tSR, not so much platforming.
I know you have the game, dibz, so you can correct me if I'm wrong but S&tSR is basically fast twitch 'press 2 to jump', 'forward to hit the target', etc. It's almost like Sewer Shark for the Sega CD (but much much better).
Don't get me wrong, it's a fun game, but in the spirit of 16-bit Sonic, it is not.
I think a rails/platforming hybrid would work better for the series and ease the transition. Multiple paths through a level, bring back the emeralds, make interesting boss battles, and you can have a winner with replay value.
I'm looking at a game like 'The Red Star' and seeing the possibilities - for TSR, the beat em up and shooter sections, if set alone, aren't very good but by combining the two there's a perfect mix of action.