The privacy and daylight benefits have proven to be true. On the downside, however, is the tremendous heat gain in the washroom during the spring and summer. We considered skylight blilnds, but that really defeated the purpose of the skylights light benefits.
The answer, solar control window film.
Solar control window films (or window tinting film) has the ability to reject solar energy either through reflection, absorption, or spectral selectivity. You must be particularly careful when choosing a solar film for your skylights as the direct light that the window receives can cause much more heat build-up than windows in walls.
When choosing a window film for a skylight, choose an exterior film - that is a window film that is designed to be durable enough to be installed on exterior window glass. Exterior films keep the heat on the exterior of the window which will reduce the thermal stress that would be caused by a film that is applied on the interior.
You can purchase DIY solar exterior solar control window film from Apex Window Films online at http://www.apex-window-film-store.com/. Currently Apex is also selling static cling solar films that can be installed on the outside glass that are removable and reusable should you wish to maximize heat gain in the winter.