Here's a sampling of what they had to say:
Matt Wolf in his Theatre.com Review: "It's tempting, and happily altogether true, to describe Judi Dench's performance in Hay Fever as bliss, which is of a piece with the character she is playing: the preening actress Judith Bliss. Dench has played actresses before on numerous occasions, from Desiree in A Little Night Music and Arkadina in The Seagull through to her Tony-winning Esme in Amy's View. But a couple of go's at Oscar Wilde's Lady Bracknell notwithstanding, Dench has rarely been given the opportunity for high comic style that she seizes upon so deliciously in Peter Hall's revival of Noel Coward's 1925 play. And guess what? A supreme tragedienne turns out to be a top-rank comic performer, too, for the simple reason that, as always, she grounds her performance in truth."
Benedict Nightingale of The London Times: "This was the play that rehabilitated an unfashionable Noël Coward when Olivier's National persuaded the dramatist to stage it with Edith Evans and a marvellous supporting cast in 1964. Forty-odd years later it seems as fresh and funny as it was then—or, indeed, as it clearly was at its premiere 40 years earlier... Could Peter Hall's revival be a bit subtler at times? Some of my favourite lines went more or less missing. Dame Judi shouldn't drop the final words that betray her pose as the squire's lady and show she doesn't know the view from her own house... Chubb and Darnley might make more of their hilariously awkward attempt to sustain conversation... Yet hilarity is everywhere: Dench huskily languishing on the chaise longue or girlishly skipping across the stage as she embodies 'winsomely' in a game of adverbs, [Peter] Bowles maintaining matinee-idol decorum as he makes stilted love to a baffled, appalled and finally furious [Belinda] Lang; [Kim] Medcalf and [Dan] Stevens exuding a cool disdain that hasn't dated since the 1920s. Hay Fever was the young Coward's amused but ambivalent salute to a world that had abandoned the old manners for a new sophistication—and, yes, it still lives."
Michael Billington of The Guardian: "It is really an evening for Dench-watchers; and what is fascinating is how she triumphs in a role that goes against the grain of her natural talent. Coward's Judith Bliss is a fading West End star encased in hyper-theatrical egotism. She is also the bustling centre of a Bohemian family that treats the four guests invited down for a weekend in Cookham with a disdain bordering on rudeness. But Dench is the very antithesis of Judith. Her forte is an emotional directness that pierces the heart, while Coward's character is a sacred monster swathed in grease-paint falsity. Like the great actor she is, however, Dench turns this to her advantage. She shows Coward's Judith affecting the role of a rural hostess and getting it subtly wrong. We first see her in a rakish, Napoleonic garden hat that clashes with her clumping gumboots. Trying to entice the flannelled fool she has invited for the weekend, she spreadeagles herself over the sofa announcing: 'I've just been pruning the calceolarias.' It is the gulf between the over-studied lines and the inappropriate theatrical gesture that makes this a sublime moment."
Paul Taylor of The Independent: "Looking, at moments, disconcertingly like the late Queen Mother in her floaty, floral garments, Dench's Judith veers hilariously between striking attitudes and spouting prefabricated sentiments that derive from memories of her back-catalogue of dreadful melodramas and sudden rapid, pettish concessions to reality. It's the seamless, brilliantly timed way in which she slides from the semi-rehearsed to the grudgingly spontaneous that makes her performance so funny. There are some delectable don't-you-dare-stop-me moments when she overrides protests and I shall never forget her little oh-so-stoical scamper to the piano to play what is evidently her one, oh-so-poignant party piece for the stuffed shirt of a diplomat William Chubb who only has to touch her to become embroiled in her improvised, wholly bogus scene of staunch parting with her self-centred novelist husband Peter Bowles."
Nicholas de Jongh of The Evening Standard: "What a fresh, blissful impression this 80-year-old Noel Coward comedy of bad country-house manners makes in Sir Peter Hall's spirited production. Hay Fever has aged as well as wine, tortoises and Dame Judi Dench, who effortlessly commandeers the role of retired actress, Judith Bliss, dizzily determined to live her private life as a fantasy repeat of the romantic melodramas in which she used to star… Dame Judi, such a downright, truthful performer, is not ideally suited to the camp affectations and artificialities of the role: as a schoolboy I saw an elderly Edith Evans, gloriously sending up herself and her voice to become a definitive Judith. Nevertheless, Dame Judi's actress, briskly self-absorbed and sophisticated, striking and voicing a repertoire of romantic attitudes, singing and skipping, expertly conveys Judith's gorgeous absurdity. A hit? Yes, and a smashing one."
Quentin Letts of The Daily Mail: "There is nothing much new that can be said about Noel Coward or Hay Fever. What a relief. The poor, wretched, dogmabullied audiences of London can sit back and simply enjoy a night out with no need for 'new interpretations' or 'challenging questions'…This Peter Hall production is a classic. Just in time for May's cow parsley season we have a Hay Fever at its most irresistibly infectious… Dame Judi may look a little ancient for the role-she is a cross between the late Queen Mother and Bette Davis-but she brings kitten touches to the production. There is a moment when, for a parlour game, she has to act out the adverb 'winsomely.' She is crossing the floor to lift a flower out of a vase when she suddenly gives a little heel-clicking skip of girlishness. Sir Norman Wisdom could not have done it better."