What a piece of work is “Man and Superman”? Hard work, to be frank. George Bernard Shaw’s experimental juggernaut — deemed unstageable in 1903 — makes for three and a half hours of tangled philosophy: a blow-away light comedy weighed down by footnotes. It’s a play for changing times, a bid to throw off the past and make things anew, and yet Simon Godwin’s handsome, modern-dress revival at the National Theatre treats it as a cultural artefact. His production abandons its audience, offering no clues for decoding the text, while Ralph Fiennes plays the motor-mouth social reformer Jack Tanner like a tongue-twister challenge. You keep up or else.