1) I use it often enough. Probably at least every week.
2) It's useful largely because I can't think of another site like it, relating concepts in different works of fiction the way it does. I find it most useful to look up a work after I've read/watched it in order to learn more about it and how it relates to other things.
3) People editing pages occasionally need to put a little bit more thought/research into things, but mostly, the editor pool seems to have way too many people obsessed with popular culture (or specific works) in ways that negatively influence their editing judgment, to put it lightly. This is especially true when you see a page that is obviously edited primarily by *fans* - not critics, or impartial patrons of fiction, but *fans* (wrong angle from which to approach literary criticism, that's for sure). Also, people need to stop using tropes as in the post directly before mine here (although I assume that's parodical in that case). It's as if they're trying to hammer the sapir-whorf hypothesis directly into their brains, or invent newspeak. Tropes are useful terms but they don't have to be used eighty-six times per sentence, or treated as gospel.
Sidenote: Anyone who's read much of Troper Tales, especially the parts that have since been closed down (yes, they were that bad) knows exactly what is wrong within the editor community there.