Originally Posted by Chuplayer

Eh, I can provide a bit of information based on what I've read.

They screwed with the aspect ratio. That makes things look weird. Probably the "zooming in on Sonic" that you're talking about.

It's a complete emulation collection. These are not ports. Yet for some reason they decided to mess with the music. The music isn't emulated. The emulator just takes its cue from the ROM and plays the appropriate music from an MP3 file or something similar. Speed shoes make the music sound weird.

There's slowdown and framerate issues.

Most, if not all, codes don't work. None of that 19 65 9 17 and then A and start in Sonic 2. I don't know exactly why this is, but I'd bet that they didn't bother to tie all the different buttons to different buttons on the DS. Instead, they probably mapped a single button to everything since you only need one button to play Sonic games, or start no longer actually pauses the game but rather brings up a menu to make a savestate and quit the game to play another one while the emulation gets stopped in the background. Lazy emulation.

No multiplayer.