In our tests (roughly one hundred people) we didn't find someone not able to perceive the stereo image.
You can turn over the pages exctracting them one by one without diverting your view. This is essential to not tire your eyes and to enjoy the stereoscopic experience. The front of the viewer is detachable and can be used to view the Cross stereo pictures on the PC.
The front part can be lowered over the over the loader (even with the pictures inside!) in order to reduce the occupied space.
Limitations resides in the size of the photo: we suggest the classic 15(width) x 10(height) centimeters. Larger pictures, even with the front detached, are difficult to be appreciated without a period of adaptation or if you don't stand at a greater distance from the photo (which could determine some blur).