There is a real velvety feel to the matte paper, with luscious and beautiful blacks, which merely look like reflections on the glossy paper. It can be, literally, like charcoal, after toning, and to me glossy will never be so beautiful. Since the matte surface doesn't reflect much light, you can see deeper into the shadows, and I enjoy the hell out of that.
I also agree with Bob that the matte paper seems to be a bit more sensitive to the toners. While I believe the emulsion is largely the same in glossy and matte, there could be small differences in order to achieve the matte surface.
Anyway, to me the glossy is great, but the matte is what I love. Suits the mood of my prints better.