I love all the little touches, the way River is looking up at Mal, Jayne's hat, Book's book, and the expressions are awesome, you really got Mal's and Wash's expressions, especially their mouth's, right.
I love this, I love the animation style of drawing, and how perfectly in character they all are.
When the animated Firefly series comes into being, I vote for you to do the artwork. You have captured each and every one of them. It's all about proper face shape and those eyes! If they were any more lifelike, they'd be be telling us that they aim to misbehave. Thanks for sharing this wonderful piece. ~Lily