The screen is VERY dark when there's insufficient light. When you have sufficient light then you'll have to contend with major glare issues. I found the best place to play is in my kitchen where I have 2 fluorescent light fixtures that run parallel to each other. If I angle the screen to point between the light fixtures then I don't get any glare and can see the screen.
The little "plug in lights" don't work well at all. I've found [link|http://tritonlabs.com/|Afterburner], which I've got on order. It's an "internal lighting" solution that will requires the GBA to be opened up to be installed. Take the [link|http://www.portablemonopoly.com/|Portable Monopoly] link for more info(note: Hasbro's after them for using "Monopoly" and they're changing the links, not sure how much longer this will be valid - they're going to move everything to the TritonLabs site).