7.9 of 10. Not that 2015 had much competition, but this is a well-thought out story based on a book. Both family friendly and something parents will enjoy watching with all their kids.
The one drawback is the ending tries too hard to make a happy ending out of a tragedy, probably because it's intended for kids for the most part. I wonder if it's even allowed to make tragic films intended for kids, some sort of secret rating rule.
For the most part, this is one big allegory made into a tightly integrated cartoon involving kids, snow, and building snow forts. There's a little romantic tween interest going on that should keep teens interested. Importantly, it's not forced and a vital part of the story.