The rolling was the only thing that bothered me, and even then there's only a handful of situations where it feels like rolling will help you out but instead you slow down and get hit (there's a big slope in Rooftop Run where you either have to stop and spindash or know before hand to jump over a long row of badniks since rolling won't get you through all of them). Everything else like the Spindash on STEROIDS and different bouncing mechanics were fine since the levels were genuinely built around those quirks, and the scripted hills are so unnoticeable I didn't even see it noted until people started hacking the PC-version.
I mean they weren't perfect by any means but you seem to be exaggerating how bad Generations' were and ignoring that in Generations those physics more often than not feel perfectly fine, as opposed to S4's where boosters and the homing attack just seemed to be there to make the game semi-playable with Rush's physics. Though I'll agree I'd prefer something closer to the older games physics than Generations in Episode 2, but Generations was billing itself more as a 'remix' of old stages than a sequel in the first place. It can sort of get away with being a bit different.
Also new badnik designs instead of Episode 1's rehashes (though in comparison to series like Mario which will always have goombas and similar cases, it wasn't too big a deal for me) make me
The prospect of a re-skinned Marble Garden makes me D: (though damn if that level didn't have a nice tune)