I've played 2 hours of the game so far. Contrary to the teaser and to Sharky believing that this would be better than Sonic Advance - it's not. It's a very fun endless runner, but it's not a traditional 2D Sonic title and it does not stack up against those. Still, the game has some very attractive graphics with 3D stages and black outlines around the characters making them stand out easily. I also dig the redesign of Sonic for the game, with a slightly smaller body and shorter quills, it's actually very much like the nendoroid figure and I'm hoping this is a redesign we will see again in the future.
As for controls, you tap to jump and can triple jump. There is no homing attack, and the spindash occurs automatically when you hit a downward slope but unlike boost pads in games like Sonic Boom: Shattered Crystal you can cancel out of it with a jump. I've also not seen any boost pads in the game.
I do like the progression, with the story advancing based on how far you're progressed through the runners segments. Sometimes you might be on a streak and playing very well, and when you die, you go back to the story and progress through a full episode through to the boss. The cutscenes are super low tech, just talking heads of still frames, but the writing is pretty good and they make reference to games like Sonic Colors which is sure to please fans who like a bit of continuity.
As far as IAP goes, it's really not that invasive. There is no "gas" refill like Crazy Taxi City Rush, or a meter like in Jump Fever. You can play as much as you want. I've also yet to see ads, or "watch an ad to get rings". You earn a good amount of rings and red rings in the game, and I've yet to see any reason to spend money (which I guess is a bad thing for SEGA).
It's a fun game though, I like it way more than Dash and it is much more fitting for Sonic than Jump was despite Jump being a solid game.