Here for "Cymbeline Refinished", a rewrite of the last act of Cymbeline which Shaw thinks "one of the finest of Shakespeare's later plays" but which "goes to pieces in the last act" in a series of absurd revelations where all the characters bar Posthumus lose their individuality. The rewrite is a bit half-hearted - Shaw says that anyone mounting the play in a version that includes the last act's dream sequence, where Posthumus has a vision of his family and Jupiter, and the means to do this fantastic scene justice, should do it just as Shakespeare wrote; but since everybody cuts that out (it was generally thought to be a later addition full of doggerel not worthy of Shakespeare), far better to do Shaw's version (in defending the very idea of rewriting Shakespeare, Shaw tries to distance himself from the likes of Cibber and liken himself instead to Wagner going at Gluck or Bach reworking Legrenzi). I'm not sure why Shaw thinks the dream scene improves the quality of everything else, but nevertheless that's his view. Anyway, in his refinishing, the dream scene goes, as does much else - it is hugely shortened, with less than 100 of Shakespeare's lines surviving. The most striking substantive change is that Innogen no longer happily accepts Posthumus's return, but instead is pretty angry that he tried to have her killed and has now, I mean right now just this minute, punched her in the face; she returns to him, but resignedly: "I must go home and make the best of it as other women must". This is a pretty reasonable change from a psychological point of view, but Cymbeline isn't a play overly concerned with psychological accuracy - Innogen behaves as she does because it is what is required by the play's happy ending (and it's been argued that Cymbeline, more than most of Shakespeare, is a play in which characters are aware of their own roles and duties as characters). Shaw straining to rework Shakespeare in the image of Ibsen (he sees Posthumus as an anticipation of Mrs Alving in Ghosts) results in something sillier than the original. Also, he cracks jokes, pretty broad ones, pretty bad ones.

Not much as a piece of theatre, then, but a useful example to cite when you want to bring up the last act of Cymbeline, which people do.