This was one of the best movies I've seen all year. I took my daughter to see it and she was captivated. She even got up in the theatre and danced around like the penguins. (It was a very empty theatre on Christmas Day, thankfully!)
I loved how the film could work on very many levels. I've read other reviews, and just about everyone who's written about this seems to have their own perspective on the movie. I think that's what works best about it. There are a lot of ways you can look at the theme of the movie.
I think the movie is mostly about how one person can really make a difference if they are not afraid to do what they do best. Mumble's gift is dancing and by not being afraid to use that gift, he changes life for all of the penguins. I think this movie is inspiring and great for kids to watch. A lot of people think that what they do doesn't matter, but everyone can make a difference, like Mumble does in this movie. :)