I'd heard ever from their launch that people had been complaining about the screen - and once I saw one, I saw why. A friend of mine has one, and you're right, it needs *very* strong light to be any good at all. It's great in strong sunlight, if you don't mind getting sunburnt while you play :) The Worm Light add-on isn't bad, but it's really hard to avoid a patch of glare, and even then the brightness isn't uniform across the whole screen.
He's ordered an Afterburner, can't wait to see first-hand how well it works. In the meantime, I'll stick to playing Spy Hunter, Glaxian, and Bejwewled on my Visor Prism. Heh, at least it's backlit :-)
Edit: A typo in the Subject line - unforgiveable!
Edit2: *sigh* Subject line should be right this time...