Best function is that after you follow/are followed by people..... When you browse, you can browse by "connections" and only see questions asked or answered by those people thus weeding out a lot of the garbage that you don't care about.
Basically, it's a direct way to find a person and to view where they last answered, to follow someone who interests you. You can find them quicker to see what was recently answered, and you can leave comments if you like. : )