It's Sonic: Collecting chaos emeralds, running as fast as you can, defeating the boss, bland plot, but very fun to play.
It's old Sonic, but faster, and with another playable character (Blaze) that is...almost exactly like Sonic.
But i did not mind playing the same game twice with both characters, is just fun to go around blasting enemies and doing loops.
You have 7 zones that consist of 2 acts and one final boss. And then two separated big bosses.
You can get chaos emeralds in bonus stages with Sonic, Blaze on the other hand gets them simply by defeating the boss of each zone.
Those bonus stages are the only place you'll use the stylus, and they are fun, even if the last one is a bit hard.
That's about it, fun everywhere, that's why this game is very good.
But why's not a masterpiece?
The bosses are a problem to me, except the one in the final zone, which is hard and fun, because it's complex, the other ones are so simple they get boring fast. That's probably because they all have 8 lives, including the easier ones, and that's to much for a boss which 2-3 predictable patterns
And on another point, the plot is ridiculous, but i'm okay with that, it's Sonic, who cares? The problem is those cut-scenes feel like years in a game with this fast of gameplay.
Overall, a great game, with some boring bosses, but i recommend it, also skip the dialogues.