I'm like three years late to this, but I've started Sonic Frontiers and so far I'm really liking it.
I think it's a great first pass at an approach to 3D Sonic. I hope they actually iterate on it.
The whole free roam running around is just good, clean fun and they should do it more.
Dunno if it's just the green setting, but I get big Gran Pulse FFXIII vibes off the islands with how desolate they are and all the enemies flying around.
On the annoyances side, like with pretty much every 3D Sonic, occasionally the camera fucks me up but it's pretty solid generally.
The levels of pop-in can be a bit jarring as well.
I'm not very far in at all yet, so maybe I'll get sick of it, but so far I'm a big fan.