So this is my first Sonic game and I honestly don't get the appeal. The level design is a confusing mess. Sonic is supposed to be about speed, but the level design is a big hindrance to that... Sonic moves too fast for the type of platforming they require you to do and needing to "earn speed" isn't a very good argument. You can speed-run just about any game through trial and error (that is to say by learning the level lay-out), but no other platformer markets itself around the concept of speed. The mine kart levels in the Donkey Kong Country franchise do a far better job of fast platforming than Sonic ever has. And what's with all the loops and springs? What does that add to the gameplay?
I've also had a few deaths that were no fault of my own... Like in the train level Sonic just jumped off the plane and went through the train as if it didn't exist.
And what's up with the stupid life-system? Only 3 lives to complete two long levels with two bosses? I've had to replay multiple sections numerous times because I died at a boss. The whole ring system also seems incredibly dated to me. Just give me a normal health meter and get rid of lives, they serve no purpose other than to annoy you. And the level design obviously tries to encourage exploration, so why is there a 10 minute time limit? I didn't even know there was one at first and died... If you're going to have a time limit make the clock count down instead of up at least... I hate games with time limits, it's why I gave up on Luigi's Mansion on the 3DS in one of the final levels (the one with the invisible time limit they never bothered telling you about).
Sonic seems stuck in the arcade days where lives, time limits and one hit kills made sense. It's 2017 however and arcades have long been dead (outside of Japan). Sega should take inspiration from Nintendo, they got rid of all those things in Super Mario Odyssey (the time limit annoyed me a lot as well in Super Mario 3D World).
If this is Sonic at his best than I'm surprised he was ever able to compete with Mario. Style over substance if you ask me.
Music and graphics are top notch though, and the gameplay isn't all bad, there's fun to be had. If only it had a better life system. That Puyo Puyo boss battle was also neat.