Doesn't a transflective LCD have a backlight? The media/FAQ page says pretty clearly that the device has a reflective LCD with no backlight, same as the GBA, which the parent comment was referring to.
As far as I'm aware these LCDs switch between black or very reflective silver and not so much black and white. Doesn't really matter what the ambient conditions are since the black is always reflecting way less light than the silver.
