So far, frontiers is turning out great in the eyes of the public.
Having played it myself and now the western sonic fans being able to play it ((EU anyway))
Everybody seems to be praising it and saying its good to great.

So its safe to say, everybody will at least enjoy frontiers to some degree but there seems to be a big problem with one aspect.

Cyberspace
So cyberspace seems to be a mixed bag, between the casuals and hardcore sonic fans.
When early impressions were coming in and even far back early leaks, everybody has said cyberspace is the highlight.
But now that hardcore sonic fans that are based in EU have tried it, all been mixed to outright not liking it...meanwhile every casual fan to journalist or even new comers have enjoyed it extremely.

There is clearly a disparity.
Why is that?
Is it because most hardcore sonic fans are the ones playing sonic daily? I kinda think so.
They grown accustomed to sonic physics in unleashed and gens and if its nothing like that, its not good enough since that's what they've been playing for the pass 5 years because they certainly wasn't playing forces or sonic colors ultimate.
On top of the Many MANY fan games/mods that build off of gens and unleashed.
Playing a boost game that's noticeably slower and feels different is gonna feel strange.

With casuals; they don't really play sonic games as much, so the physics and speed of them is no problem, its kinda like their first time.
They don't have games to compare to like unleashed, gens and even colors; even if they did, they don't take it as such a big issue and can still enjoy what is offered without being bothered by the little nuances of different physics like sonic being a bit too floaty or sonic being a bit too stiff.

I am such a person.
I don't consider myself a casual fan.
I'm a MASSIVE sonic fan but I'm also very lax in what I enjoy.
I don't have this crippling PTSD from forces as I don't think forces was the worst thing ever made but it was subpar.
I totally enjoyed cyberspace and at first I was confused as to what people were talking about as to how sonic felt...because in my opinion.
Sonic felt the same as in open world. Just a bit heavier as I can tell the tuning was different but he felt basically the same.

But a lot of hardcore fans felt very differently, they outright hated cyberspace or just said it was "med" but better than forces.
But nearly all of them has said that cyberspace is for sure the worst part while critics/ journalist have said its the best part.

Now this has me thinking of a recent interview I saw....kishimoto talked about action mode and high speed mode and sonic's speed and basically a new philosophy

He said: "By adding speed to an action game, I think it's a series that has brought a sense of speed and excitement that you can't get anywhere else. But while fans of the series are looking forward to this stimulation, when I thought about my goal of aiming to be the top of the world once again, I thought, ``Sonic that can only please Sonic fans is no good.''

So it made me think, cyberspace is probably tuned the way it is for people that want to play the series but too scared of the fast pace of it.
This is probably why sonic is slower in cyberspace and thus makes him more controlable for new comers.

Kisimoto-san really wants this game to appeal to everybody and I gotta say....it is working as you are all aware, nearly every critic has enjoyed cyberspace...but this move is ultimately good for the series.

I know in japan, a lot of my friends are intimidated by sonic due to how fast it is and sonic being slown down on linear levels gives people courage to try traditional stage clear zones.

Overall cyberspace is to appeal to everybody and quite possibly mostly the new comers; current sonic fans still get their stage clear traditional stages and new players get to enjoy them a decent pace as sonic is not as fast as...say..in unleashed where he was the fastest.

And whether you like this or not.
I think we can all agree accessibility is better than it just pleasing one side, sonic can't grow if its only going to cater to one side and kisimoto/iizuka understands this.
Who knows...maybe in a patch they'll allow us to change the sliders in cyberspace((as I think this would truly please everybody)) though I don't see this happening as it would break the ranking system.