This three-act play (or series of playlets) is thought to be a comedy. I consider it a tragedy.
In each act or playlet, the characters have been going about their business, living lives of quiet desperation, until a central event which occurs during their stay at the Plaza Hotel in New York City blows their world right open and reveals to them how pathetic they truly are. The difference between their aspirations and their reality is too stark to be ignored.
I'd be curious to know if anyone who has seen this performed live had a different experience. The audiobook (which was produced in the late 1980s with an all-star cast) made the material seem dated and the characters appear to be mere caricatures. This was not the best exposure to Mr. Simon's work.