You will probably say that I'm about to write some stupid thing about 3D effects and visually impaired persons. You are wrong: Beryl can bring really useful features to the linux desktop for these persons. Many of them need reversed colors and/or a magnifier on their screen. Even if there already was Orca having these features on Linux, they were not so good compared to what can be done with Beryl. Just forget the 3D cubes and lovely effects, but try to play with + mouse wheel or + m. Those shortcuts can magnify or reverse the whole screen easily and let me think that we could find some usability improvements for persons who have some difficulties to read on a screen. Just see this screenshot, which is the copy of what I saw on my desktop (it hasn't been cut afterwards).

Beryl magnified screenshot