Didn't see the play but I remember when it ran. It is the only play I can think of that played the Broadway Theatre because the show has a huge cast--as big as a musical. It starred Jason Robards and Anne Bancroft and got a very mixed reception. It ran all of about 6 weeks plus some previews. I can't remember if it went on a pre-Broadway tryout or not.
But, a here is the trivia aspect; Bancroft started missing performances fairly soon as was her wont in her later Broadway appearances. Her understudy/standby got a lot of attention both from a critical standpoint and a press mention standpoint.The understudy went on a lot, especially for a 6 week run. Her name was Zoe Caldwell. Yes, the Zoe Caldwell.
Immediately after The Devils closed, Caldwell was cast in a featured role in Slapstick Tragedy by Tennessee Williams which opened at the end of February and ran 7 performances. Caldwell got uniformly great notices and at the end of the season won a Tony.
The next season she starred in Jean Brodie, won another Tony, and the rest is history.
Ain't that sweet?