If you have a great room (lighting control, dark surfaces), this Sony can rise up, and handle some rather respectable screen sizes. I viewed HDTV source material as large as the equivalent of 131" diagonal for 16:9 aspect ratio, and could tolerate some controlled ambient light.
If your room is more family room, and don't want to be watching football in a cave, where you can barely see your buddies, figure you can handle up to about 110" diagonal with limited controlled ambient light, and still have an image that looks fairly dynamic. Kill all the ambient, though, and 110" diagonal should look downright great, with about 1065 lumens in "brightest" mode.
Below: No, you aren't going blind. While there may be no practical way to photograph a projector doing 3D, so you can see what the 3D looks like (yet), below is a photo from a football game broadcast in 3D. You can see the double images!