I wouldn't call this a review, but since my whole family has been playing it non-stop since Tuesday, I have a few observations.
First off, the whole game is a SegaSonic take on SatAM. The small band of Freedom Fighters are opposing Eggman's world takeover. The mission menu is even kind of a Risk layout, with gray for Eggman sweeping across the land, and the blue of the good guys pushing back. I think Sega paid very close attention to the tropes that the fandom likes the best. For instance, SatAM. People LOVED the Freedom Fighters setup. People have made their own Freedom Fighters and fanfics about them for years. The comic, even now, hasn't strayed too far from that same formula.
The Sonic games have told stories all over the place--werewolf Sonic, Sonic in space with space aliens (Colors), Sonic in whatever Lost World was, Sonic Heroes, and so on. All very different games that kind of hit all over the map as far as fan response.
You can tell when the fans grew up and started creeping