Here is a sampling of what they had to say:
Ben Brantley of The New York Times: "With its chipper aphorisms about finding the courage to be yourself and its dominant theme of mending a torn family, this Mary Poppins addresses the conscious part of the mind that keeps self-help books on best-seller lists. But as designed by Bob Crowley and choreographed by Matthew Bourne, the show's imagery is pitched straight to the id. This tension both makes Mary Poppins bearable for restless adults and keeps it from sustaining the joyous sense of wonder it is clearly reaching for. Even at a hefty three hours, Mary Poppins is not a bore. But neither is it a rip-roaring delight."
Benedict Nightingale of The London Times: "Long before Laura Michelle Kelly's demure Mary has zoomed over the stalls into the theatre's star-splattered eaves, this marvelously fresh adaptation of P. L. Travers's stories had clearly won the hearts, minds, eyes and ears of last night's audience. I don't think it was just theatre chauvinism that left me thinking the show better in every way than the Disney film, delightful though that seemed 40 years ago. Thanks to Matthew Bourne's choreography and Bob Crowley's designs, those ways extend to the visual, and, thanks to Richard Eyre's direction and Julian Fellowes' book, certainly embrace the content… Supercalifragilisticexpialidocious--or so I'd say."
Nicholas de Jongh of The Evening Standard: "I never thought in my wildest theatrical fantasies that Walt Disney's syrup mountain of a film that has melted the hearts and softened the faculties of millions of children could be worked up into such a sharp, thoughtful stage musical. The show's appeal is not just to juveniles, who will be captivated by Miss Kelly's pert way with magic and that Spoonful Of Sugar, but to adults at whom the stringent, talking stuff is aimed. Julian Fellowes, who has written the show's new book, has returned to the original writings of Poppins's creator for guidance… The musical and spectacular aspects of the overlong production, which drags in the first half, are less interesting than its narrative. Miss Kelly's passionately sung Mary cuts such an enigmatic, elegant and emotionally detached figure that she rivets attention as she faces up to Haig's highly comic model of ill-tempered, anxiety-laden pomposity, whether at home or at the bank."
Quentin Letts of The Daily Mail: "Two things one never expected: Laura Michelle Kelly, in the lead role, is an entire category better than the great Julie Andrews; second, this stage version has much much more punch than the adored old film version. The show contains plenty of the Sherman brothers' wonderful song such as ‘Let's Go Fly a Kite' and ‘Chim Chim Cher-ee.' Part of its charm, and the key to the huge success it will undoubtedly be, is that it automatically feels familiar. But there are also new songs, of equal quality, from newcomers George Stiles and Anthony Drewe. The miracle of their work is that it too feels like an old friend, while injecting much welcome modernity. This production is certainly no mere kids' night out. It makes you cry, and there are moments that will give fainthearts cause to shield their eyes. But children of eight to 80 will feel boosted, liberated, shimper, and hide their eyes. With her brolly and her brio, this bird has plenty of bone in it. She flies."
Sheridan Morley of The Daily Express: "What the producer and co-creator Cameron Mackintosh has brilliantly realized is that Poppins belings, like Peter Pan, to a Never-Never Land where all dreams are possible. For Mary Poppins is also about flying, her chosen method of arrival and departure, and this is also essentially a children's play with songs, which is why I believe that, like Peter Pan, it will live for as long as there are children to celebrate it and be amazed by the wonder of human flight. What Mackintosh and his director, Richard Eyre, have done is to restore the human dimension, so that we focus on an apparently fairly normal family. Mary Poppins brings back a lost age in which children were treated as intelligent theatergoers in a story which, albeit dark around the edges, took them some way into the secret garden of adulthood and reassured them that it might not be so awful after all. The nanny has landed..
The Independent: "With its magic and chutzpah, it simply blows away the opposition from rival West End musicals, emerging as the year's most joyous, spectacular and heart-tugging show in that genre. Don't turn up expecting a dutiful transfer from screen to stage. True, many of the much-loved Sherman Brothers' songs are here, but there's no merry-go-round horse race, no dancing penguins, no tea-party on the ceiling. Instead, the show, directed with huge flair, by Richard Eyre, has been reworked to incorporate more of the original P.L. Travers stories and it often finds exhilarating new contexts for the old numbers… There's a batch of strong new songs by the English team of George Stiles and Anthony Drewe and a wonderfully fresh take on the book by Julian Fellowes… As for Laura Michelle Kelly in the title role, she's superbly tantalizing and enigmatic."