Frank Langella portrays Richard Nixon so well that you would think he rose from the grave to play the part himself. Not being as familiar with David Frost, I do think Michael Sheen played him well based on what other people tell me he was like.
As far as the play itself goes - too long! You do not keep an audience in the seats for 2 hours without intermission! Aside from that insult and injury - the play also had far too many filler and back story elements. Yes, we needed to know that back story to both sides, but possibly not as much as we were given.
Maybe this was just my expectation, but I thought we would see more of "the interview". I mean the play is billed as "The Face Off of the Century - Live on Stage" I think if they flipped the balance, the play would naturally build up to this important interview and you would be absorbed in it's progression and the drama could have unfolded within it. Instead, by the time the interview rolled around after 1 Hour and 30 minutes - you were anxious and trying to figure out how much longer this thing was going!
The rest of the cast was marginal - partially because some of the parts were written as marginal characters, but the the other ones were just played by marginal actors i suppose. I felt a vast crevasse between the talent of Frank Langella and everyone else. Or perhaps that was done on purpose? Isn't that how Richard Nixon was in real life - larger than everyone else?
In summary, a superb performance by Frank Langella that was neither matched by the rest of the characters in the play or the actors cast in those roles.