Now that the game is out, here's something interesting when it comes to the PC version graphics and anti-aliasing.
Just found out that forcing anti-aliasing through the drivers (at least on AMD graphics cards) works for Sonic 4 Ep 1, but only at certain resolutions. So far from what I've tested, it works at 1280x720, but doesn't work at any other resolutions I can use. My screen goes only up to 1440x900, and the only 16:9 resolution I have for Sonic 4 Ep 1 is 1280x720, so it's possible that either AA only works at 16:9 resolutions for Sonic 4, or it only works at 1280x720.
Anyway, here's pictures showing the difference between no AA and 8x AA.
No Anti-Aliasing:
Forced 8x Anti-Aliasing through the AMD drivers:
EDIT: Here's Sonic from both of the previous pictures, but zoomed to 2x.
Left is no AA, right is 8x AA:
EDIT2: Tried this on my brother's PC (he has a 1080p screen), forcing anti-aliasing through the drivers only works at 1280x720, at least on AMD/ATI graphics cards. It didn't work at any of the other resolutions.