Finally saw it
I was curious about it, so I watched it on my own. It certainly wasn't as boring as the original "Marry Poppins," and even more colorful than the original. Sad part is, it's very predictable and probably only memorable by kids' standards, but I wouldn't prevent kids from watching it. They at least explained Mary's magic more clearly, and even showed other people like her in the film. It was especially surprising seeing Angela Lansbury again.
I'd give it a B rating: okay, not great, but watchable. I think Walt would have liked it. He probably would have also been impressed by the CGI technology used, compared to what he had in the 60s.