Someone suggested using it to identify things you only remember bits of or certain scenes from. I tried using it to find this YA book I read as a kid; it was not at all helpful, but did eventually lead me to do researching and finding the book elsewhere. (And it turns out the scene I was describing was exactly what happened, and the characters were named exactly what I thought they were, so that was born annoying at the time and frustrating later.)

I also tried using it to find this really obscure, incredibly bad 1970s tv movie that I had vague recollections of. Again, the scene was pretty much what I remembered, it couldn't identify it, but I eventually found a site that lists the plots of old tv movies and I read through like 30 pages of movie synopses until I found the one I was looking for.

I've also tried using it to find this 1980's interactive fiction game, but it's proved useless once again - and once again further research has identified a couple possibilities except I haven't had time to try to find the game and set up the right environment for it.

So my experience has been that it's useless in finding the things I want it to find, but that in trying to persist against it may lead me to find what I'm looking for elsewhere.