I have a Macbook.. here's my 2cents.
Outside - unusable. Even in the shade of a tree, I can't see anything. I've heard of people using it outside with no problems, but I can't for the life of me see anything but the reflection of my face! I've tried tilting the screen (which only tilts so far), messing around with brightness - it's hopeless!
Indoors (library, classrooms, lecture halls, etc.) - usuable. Occasionally there is some glare, but nothing serious.
Outside - unusable. Even in the shade of a tree, I can't see anything. I've heard of people using it outside with no problems, but I can't for the life of me see anything but the reflection of my face! I've tried tilting the screen (which only tilts so far), messing around with brightness - it's hopeless!
Indoors (library, classrooms, lecture halls, etc.) - usuable. Occasionally there is some glare, but nothing serious.