“If a work is quite perfect,” wrote W.H. Auden about Hamlet, “it arouses less controversy and there is less to say about it.” Across four centuries, critics have found plenty to discuss in this longest of Shakespeare’s plays (also one of his most frequently performed). Auden is prominent among those viewing it as severely flawed. Director Robert Icke has joined the colloquy with an absorbing stage production, now at the Park Avenue Armory, that handles the script’s ostensible defects with aplomb and, in so doing, refutes T.S. Eliot’s suggestion that Hamlet is an “artistic failure.”