I still say it's too early to judge. However heavily it may borrow from Sonic 1 and 2, it's still a sight better than what we've been getting. I think Sonic 4 is a case of "the road to Hell is paved with good intentions"; the Homing Attack, physics, and Rush path design may not work well, Splash Hill's music is grating my ears, and yes the bloody thing is episodic (but so is Shantae, and who's complaining about that?).
But we do have Sonic 1 Chaos Emerald collection and Super Sonic back, we're squaring off against Egghead/Robuttnik, and the teams may very well be trying to design the stages as a merger of the better parts of Sonic 3, CD, and Rush styles which would be very close to ideal, so I say we wait and see.
And remember, Sonics 1, 2, and Knuckles weren't exactly "gems", either. That's probably why they were so hated for the longest. Sonic 1 is slower than Antarctic Molasses, Sonic 2 drags on way too much and the goalposts are too scattered to make Emerald collection fluid, and S&K's stage design post-Flying Battery is *BEEP*.
Sonic games are best judged when we get it in our hands, not by vids.