The Finest is hard to describe.
Technically, it's a sort of waiting room for a few characters before a game begins, and you can use it as a sort of atmospheric prelude or interlude to a campaign. It takes place in an isolated area where other characters cannot reach, and significant dramatic actions in it fail.
It's also sort of a larp, in that any undertaking you want your characters to perform takes in real life the same amount of time it would take to perform in game.
It's also sort of a prison, in that the rules are pretty clear that it takes hold of you and does not end until it is over.
Apart from being a strong concept game, I can see probably two uses for it. One being a fairly intense, quiet prologue---which I think a lot of games would benefit from. The other would be to simply make the game a Delta Green monster, which I think it would work great as.
Either way, I do recommend picking up a copy and checking it out.