The best thing about this is the facial expressions. They're all so, well, expressive. Heh. Remus' pose makes me think that he's either in the midst of coming, or right on the edge and trying desperately to hold out just a bit longer. And Sirius looks like he simply can't believe his luck. Haha.
Also, Remus gripping the table cloth and his hair spilling onto the table -- guh. The fairie lights all around are gorgeous and festive; nice touch.
Niiiiice (and very appropriate...) way to kick of the fest, I think! :D