The iPad (and iPhone 4) use a new type of screen with IPS technology. [1] I find it to be much nicer on the eyes than a regular display. It also works really well in direct sunlight, as long as you don't reflect the sun directly into your eyes. Sort of like reading a glossy magazine outdoors.
[1] http://en.wikipedia.org/wiki/TFT_LCD#In-plane_switching_.28I...