I was also at the Saturday matinee and was surprised by the rows of empty seats in the back of the orchestra. I recall much fuller houses at last summer's A New Brain and The Wild Party.
As for the show itself, I found it to be completely charming especially in the hands of Santino. What a star. I also really enjoyed Rebecca Naomi Jones and Brynn O'Malley. Contrary to how earlier posters might have felt about the cheese nips song, I thought O'Malley's delivery of it was hysterical. Rebecca Naomi Jones had a great moment with her line about the Rosewater file having gone missing; the campiness of her delivery was just what the piece needed, and I think the production itself would have played even better had more moments like that been found.
I also want to comment on the use of the scripts. I understand the abbreviated rehearsal process doesn't always allow enough time to commit lines to memory, but I was off-put by how badly certain actors were still stumbling despite having their faces buried in their scripts. It's one thing to be noticeably reading off of the page but to be constantly tripping over your words is another. And for what it's worth, I'm not referring to James Earl Jones. I hardly noticed him referencing his script. All in all, though, it was still an enjoyable afternoon. Add me to the camp that's hoping for a recording of this cast.