The film itself was entertaining from an adults point of view. Of course the magic isn't quite the same as when you were a child.
Saying that, Emily Blunt was more Nanny McPhee than Mary Poppins. Julie Andrews Mary was bright, fun, motherly and smiled a lot, all the things you loved as a child in a nanny.
Emily on the other hand was wooden, sour looking and rather like a cardboard cutout. I liked the dance routines, specially the Lighters and their lamps. Overall it was good, but Emily spoiled it.