Sonicdissected 11-4-2

Your guest says at first, that in the old games you would receive a feedback (illustrated at the last boss). Yet one of the things that gave you feedback was when you were hit and by that you were pushed back, stunned and generally confused. I am not saying that is bad. In fact, that is just the appropriate kind of punishment you should receive.
Yet in Sonic Generations when you are stunned and confused, it is suddenly bad?
You don't ever find me defending that game, but from the purely gameplay aspect, I don't understand how it's so much different. The fact that it is in 3D and you are moving in the whole volume (not just on the surface like in SA1) makes it confusing by default.
The mankind - in contrast what you and many people may think - is not used to think in 3D. When it comes to 3D, our imagination suffers greatly. Everything becomes a mess.

I can give you two examples:
Imagine you have a cube. You hang it on a rope attached to one of its vertices. Now you rotate it. Draw the rotational object it creates. 90% of the people wouldn't know how it looks like if they did not perform the experiment.
Another example - imagine a room without windows and doors (now light is not any of our concerns, now I speak only about geometry). That room has completely random shape, the only requirement is that all the walls are planes (but they can be triangles, octagons, whatever). Now you place a camera in each corner of the room (the camera view angle is only hindered by the neighbor walls). And even despite in every corner there is a camera, there is still a region of the room that cannot be seen by any of the camera. What is the shape of the room? And where is that region?

3D space is confusing by default. That may be the reason why so many Sonic fans hates 3D. It's too hard to think in 3D. It's not very relaxing on a certain level of brain activity.

But she is right that when you do something important while fighting the boss, there should be some more visual clues. But I almost think that they made it confusing on purpose. The boss is a creature that can manipulate time. That's even one more dimension above the 3D. Maybe it fits the story that it is so confusing. ... Well, the "story"... Yeah, I eliminated myself with that argument, OK, I surrender.