How does everyone forget the touchscreen? It worked extremely well for shooters on the DS
So how does this work exactly? You hold the 3DS in your left hand, while also controlling the left analog stick with your left thumb, and then aim/shoot by tapping where you want to shoot on the bottom screen, with some kind of 3D reticule on your top screen? I don't know but I feel that with the separation between touch screen below and 3D display above, things have gotten more complicated for the 3DS than before on the DS. Also seems to me that you're not going to want to switch between looking at the 3D and the 2D screen very often ...
The gyro could help here and there, but then 3D holds you back as well. I think there are going to be some games / genres that will struggle to support 3D.