Not only do they apparently complete the movie in one take, they even work in a flashback by redressing a set on the fly. There is a scene in the middle where Bettis giggles, thinks she's blown the thing and says "sorry", but the other actors keep going and they soldier through to the end.
Dramatically, the technique lends itself to making the events seem dreamlike and unrelenting. Of course David Lynch did the same thing for years without that sort of gimmick. I also thought it tipped the ending really early in the game, though that probably makes the movie make more sense.
The story takes place in several locations (and by necessity, all points in between), which is a daring stunt on its own. The story takes place in the wee hours of the morning, so sunlight vs. artificial light doesn't seem to be a problem.
Was it worth it? As expected, it's more interesting than good. Form trumps function. Probably not recommended generally, but as a demonstration of some daring