It's terrible. I can only see the keys in bright light or very dim light. Anything in between and I have to tilt the device at all angles to read whats' on the keys.
I got sick with it as well. So I bought a new black case and keyboard from cnn.cn. Now I have a nice new bb that I love and the keyboard has excellent readability.
Posted from my CrackBerry at wapforums.crackberry.com
I just replaced the keyboard with the black one with white lights (partial replacement as opposed to efk22's full replacement). I also purchased from cnn.cn.
I am not sure what the visual/optical issues are with the blue lighting but many of us have determined that it is really hard to read.