Played this at EGX today, surpassed my cautiously optimistic expectations
I played studiopolis, which had elements of a sort-of greatest hits of Sonic tropes, with checkpoints from 1, star music and power-ups from 3 but the overall aesthetic stylings of a sort of 2+. The view seems to be a little closer, with the sprites and general size were a bit chunkier on screen than when you play Christian Whitehead's slick phone ports, and looked great without compromising navigability at speed. And the level felt whole and distinct and not like the sometimes sprawling samey-ness of Sonic CD's.
More importantly, the level was ace, with great music, a unique visual theme and lots and lots of pinballing fun with classic sonic weight and momentum. It's actually (whisper it) plays better than many of the old sonic levels do so today, without arbitrary instadeath traps and soaring jumps that land straight onto badniks etc. It is perhaps a little short on challenge but as a fun house of colour, candy-machines and springs and ?sonar radars all over the place, it rivalled the sheer joy of any level in Sonic 2 (which i just replayed the other day on my phone)!
There's also some new through-lines and bumper combinations which were fun to navigate.
Based on just the one level, it isn't the level-transforming, boss-chasing set-piece stacked epics of Sonic 3 or S&N, but more like a celebration of Sonic1/2-style purity.
And it was great