Right, so, this is literally just Sonic 2 with a few tweaks to the level design, different bosses (including a Sonic & Knuckles-esque final boss) Knuckles as a baddie again for some reason, and 8 bit remixes of the Sonic 3 & Knuckles soundtrack.

It's not bad at all! I just don't have much to say about it.

sonic 2 2

this game is the only reason people outside of the fgc care about the ng pocket

The physics are alright, so are the visuals & music, but the special stages are terrible, and the extra goodies are whatever.