I can also see your point Khorney, and I do agree that free 3D loops are somewhat harder to control. The whole game will be harder to control, because obviously it is in 3D, but not that harder.
You can't keep the degree of freedom of the original Sonic games in 3D without a bit of added difficulty. But it's pretty much a matter of getting used to the new experience. I believe it is somewhat like on Portal, when you first get through a portal from the wall and end up on the ground and you go all: "WTF!?" But with time you get used to it, and start seeing it as something natural to the gameplay.
The added difficulty IS part of the experience, and I think it's totally worth the price. If you start thinking about it, 3D opens a whole lot of sequence breaking possibility, as long as you can get enough momentum. I'm pretty sure when (if?) this game gets done we'll see a lot of people doing all kinds of amazing things at the levels. Things they weren't intended for.
And you shouldn't expect it not to be challenging. The intended audience is Sonic fans who grew playing Sonic as kids, and now are adults or teens. If you can't expect them to keep up with the increased difficulty, if you can't expect them to learn new abilities to help them overcome new challenges, just like they did 15 years ago, then there's no more need for Sonic the Hedgehog.
The whole point of adding the WASD + Mouse control was actually to compensate for the control difficulty, in a way that doesn't feel completely unnatural. At least for me, it's the best way of playing a game like Sonic in 3D. But that's probably because I got used to playing SRB2 with it. I think it's totally reasonable for people to complain about the controls because they don't feel comfortable with them. But I think comments like "the control shouldn't be like this because Sonic is not counter-strike" are totally stupid.