This is excellent and everything I was hoping and all but what the hell is David Mamet doing on this job?

Wonderful. Really wonderful. When you're curious about how acting really works - try watching this.

Strange little idea for an art film that doesn't quite work out

One glaringly fictional, and filmic, device, however -- a single passage of voice-over interior monologue, while other characters on other occasions must content themselves with standard soliloquies -- capriciously violates the "rehearsal" premise. That last conceit aside, the movie, as its title forthrightly announces, is more documentary than fiction, a continuation of the theatrical run for one final performance, a filmed record of it. Or in other words, it's still more a play than a movie.