(A few years behind everyone else... but I was waiting to find a cheap copy.)
Actually, I'm quite glad I waited for the cheap read since this book is not as satisfying as his Three Uses of the Knife: on the Nature and Purpose of Drama. That book I found fascinating; this one, sadly, deteriorates into a rant guaranteed to irritate most Method actors and the more "visionary" sorts of directors. (I had to laugh.) But amid these entertaining swipes at over-blown acting methodology and overweening directorial egos comes some feet-on-the-ground comments about theater design:
"...the job of the designers of costumes, sets, and lights, is to increase the audience's enjoyment of the play past that which might be expected in a performance done in street clothes, on a bare stage, under work lights."
This is a very low bar... and yet a also a surprisingly difficult bar to leap over. Especially if you carry the true weight, the true cost - in money and human effort - needed to create those sets, costumes, or lighting effects.
"Why is this great rehearsal more enjoyable than the vast bulk of designed productions? It allows the audience to use its imagination, which is the purpose of coming to the theater in the first place."
Myself, I might not have said "vast bulk," but otherwise I have to agree. (Maybe I'm just an optimist.) Then, a little further on (writing from page 5 to 6) Mamet goes on to say:
"It takes a real artist to increase the enjoyment of the audience past that which would be found in seeing the play on a bare stage, for the first rule of the designer, as of the physician, is do no harm."