To some people, it just sounds like a chick wailing for several minutes. Personally, I find it quite powerful. I like her voice, I like the chords, and I like the way it rises and falls, practically telling a story without words.
But you have to consider that it's up against some songs with some iconic lyrics, words that literally apply to everyone and to which everyone can relate, talking about issues we all have faced or will someday face. We all seem to have different criteria for voting in these things, but I try to measure "overall awesomeness" based on as many factors as I can. And when you get right down to it, "Great Gig" is just a chick wailing for several minutes.