I love this strip! It presents the world of the kids in a way that makes it seem all real, like there's always a dozen things happening at once. My favorite joke in it, however, is the one in the lead two panels, which is just a throwaway but has some pleasing off-screen violence.
The metaphorical opening panel uses Charlie Brown's trademark zig-zag shirt pattern, but the zig-zag is nowhere to be seen elsewhere in the whole strip, and is in fact a little uncommon in the strip at this point considering the kid usually covers it with a jacket in the winter months. Maybe he was just reminding the reader of it.
There is a lot of prototype Calvin and Hobbes here, both in the snowman gag and the humorous sled crash at the beginning.
