I'm always reading something, usually multiple books at a time.
It turns out I was way off when I estimated I was 75% finished when I posted my earlier update today. I finished listening to this while I was still on the front porch, about to go out for today's run. So I must have been more like 99.99% done.
Anyway, the ending made me feel a bit "meh." It wasn't even an ending so much as it was a stopping. There was no resolution; no (unfashionable) closure. Which, I realize is the postmodern way to go, but I guess I've had too many postmodern none-closure stoppings.
Also, I will fully concede that much is probably lost in simply listening to a play. That whole visual dimension, with the actors' non-verbal acting, is lost. As I mentioned in my update, I do generally enjoy Mamet's work, and I will probably seek out the movie version of this from my library's DVD collection.