Sonic's final sprites are definitely my least favorite from the classic series. I loved the swirl in the running animation from the prototype, and I wish they kept that in the final game... Sky Chase zone's music is great, but auto scrolling levels don't necessarily fit a game that's based around speed. The final boss has a really shitty hit box, making it the most difficult to beat out of the classic games. Metropolis zone just outright sucks, the music is great though. Let's also not forget that the player cannot fly as Tails, but the AI can.