If you're in the right lighting conditions, blacks are far blacker, contrast is better IMHO than a matt display. But it's a very contentious issue as far as I know.
having had both matte and glossy macbook pros, my own observations seem to confirm this: colors are richer and display is brighter (across the same model) but glossy screens get smudged a LOT, and reflect just about everything
That's it. If you (the common person TM) are on a shop and look at two laptops side by side, one with a matte screen and the other with a glossy screen, I'm pretty sure that person will be more pleased with the colors on the glossy one.
