Whoot! I just watched this the other day and was pleasantly surprised! At first it really did remind me of Mary Poppins. As the plot progressed, however, I got to see the many differences, and I fell in love with the story! Nanny McPhee is a really awesome character. The whole story just was magical. The acting, I thought, was really, really good; Every actor was suited to their role.
The movie was based on the Collected Tales of Nurse Matilda by Christianna Brand. After seeing the movie, I think I may take a look at the book.
I def recommend this movie! *Linksquest's stamp of approval*