This really plays much like a filming of a play. The direction is almost minimal. That's probably for the good given that what remains is a great bit of showmanship.
Alan Bates is stunningly good as the lead Butley. He's a brilliant professor and writer at the end of his career. There is some amazing scheming between his character and younger more promising acolytes that he is jealous of.
The only reason to watch this is for the dialogue which is sharp and literate -- one wonders what became of this. The version I saw was a film version of the play. Not much of production value but the playwright's craft is still preserved. Even mentioning all of this, it's amazing how well this holds up almost 40 years later. That's probably due to Bates' bravura performance.