It's control, and until people figure out how to use the Wiimote properly, they're going to give varied reviews depending on how well they can get the control to work.
When I first played Sonic: SR, I was faced with a tutorial level where I had to collect rings by moving left and right with the Wiimote, and I didn't miss a single ring.
I had no problem with the non-upgraded Sonic, and yet many reviewers bash these games because they have a hard time with the controls.
All you can take from it is that some people will have issues with the controls while others will not. Simple as that.