^ Okay then, let's make a list of "every single worry" that you can reference when the time comes. A quick collective of most of the negative things that I've heard on various forums:
* The lack of new badniks means that the game will suck.
* The lack of new badniks means no new bosses, either.
* Homing Attack will contradict all promises of momentum-based gameplay.
* Homing Attack will feel out of place in a 2D game.
* Homing Attack will allow for a Jump Dash that will make gaining speed much too easy and make Spin Dashing pointless.
* Sonic's model being a slight tweak of his Unleashed model means that the game will suck.
* Sonic's appearance on the logo means that the game will suck.
* Sonic's model having green eyes means that the game will suck.
* Sonic's running animation sucks, so the game will suck. This is already proven wrong: the animation in the trailer is not the fastest, according to SEGA PR, and the full-speed animation will be more like the classic ones. Nevertheless, people made a stink about it, so it's in the list.
* Physics seem a bit strange in the three seconds of gameplay footage.
* The corkscrew that disappears early in the three seconds of gameplay footage is just one of many such glitches.
* There must be a bottomless pit under the corkscrew bridge in the footage, so all level designs will be similar.
* There won't be more than two paths running at a time.
* The fact that the graphics are New Super Mario Bros. style instead of Mega Man 9 style means that the game will suck.
* The fact that Sonic Team has to put a 2D game on a modern console at all means that the franchise will die.
* The locked character on http://sonicthehedgehog4.com
is actually a new playable character that will drag down the game, even after we were told explicitly otherwise by SEGA.
* This game only has one character, so it will suck.
* The promises of momentum-based gameplay are lies.
* The Episodes of the game will be too short to be worth playing more than a few times.
* The storyline will be overly dramatic like with all recent Sonic games.
* Super Sonic won't be playable in all levels, so the game will suck.
* The music we've heard of the game sucks, so all of the music in the game will suck.
* It's just plain impossible to live up to the epicness expected of the name "Sonic the Hedgehog 4", so the game will suck.
* The name "Eggman" is used in the English localizations despite the English localizations of Sonic 1, 2, and 3 & Knuckles using "Dr. Ivo Robotnik", so the game can't possibly pretend to be classic.
I'm interested to see how close your statement comes, for better or worse. If anybody else can think of other complaints that have been made that I've forgotten, edit it onto the end of the list if you can or reply with it otherwise.
EDIT: More on the list... PPA's concerns are being listed separately since he believes that the ones listed so far are "negligible, nitpicking and hasty" and that his aren't.
* It's entirely soulless and lacks inspiration, innovation, and identity, as shown in the concept art of the flower and the tree as well as the video.
* The graphics looks like someone resurrected G Sonic/Sonic Blast in Flash.
* SEGA still doesn't "get" the old games.
* Iizuka is making the game.
* The Motobug redesign is not only hideous but even inconsistent with the style of that touched up S2 MZ crab badnik, proving the incompetence of the art direction.
* Why would SEGA after a decade of utter failures suddenly make something that does not suck? They didn't even manage to ever reach the hollow and mediocre but at least decent level of Sonic Advance again! (Although admittedly Rivals went into that direction again before Iizuka came in and declared it would have to be a racing game.)
* They will warm up a few old and spent ideas to try and create what will, assuming it avoids being a catastrophe, be no more than a pale shadow of the old Sonic games. See #1.