When I put my 720 on a kneeboard in portrait mode I had to adjust the angle of the display..."flat", i.e. zero deg inclination reflected the overhead skylight, 45 deg relected my face, 30 deg my shirt, etc. In my case a 20 deg inclination is "just right". Some time ago I posted a snapshot of the finished kneeboard with battery pack and 12 v power in and an external pigtail lead for a gps antenna. Works very well for me.
Ted