I realy like this one because there aren't a lot of christmas fanarts of this series. You made a good work in the shading and colouring.
You made a great work with the expressions of each character, and paid attention to some details, like the shading of the tree's ornaments, and the Dangos everywhere.
The only problem you could say is that the characters don't look exactly like the series, but since you made them in your own style, I think that's perfect.
Making things in your own way is a perfect way to gain your identity and eventually improve the technique that suits you better.