I have been meaning to write a critique on one of your works - and this one in particular - for quite some time now, yet try as I might, I never seem to find the proper words, and not even now can I say that I am certain that the words I use are worthy enough for what you delight us with.
Now, it is my opinion that one must never try and rant about how "incomplete" some works are, for then critique in itself would fail to have a point. The sketchiness in the first two "pictures" gives one the feeling that he (or she) is looking at one of those terribly old, terribly rare and also terribly beautiful Disney character sheets and concepts, and that is instantly a "+" in my book. Sketches are a work of art, no matter what.
BUT - the finished colored DIGITAL piece still captures the viewers' interest in a flash! (especially when Vole has that "aha!" kind of look ... lovely!)
Also, considering who this character actually is (mouse-Lestrade much? how awesome is that!) all I can think of saying is "congratulations!" Taking an already existing character from books and such - where little to no images or references are provided - and trying to give it shape (or how I like to call it: "life") is by no means an easy task. But your Vole looks perfectly in character!
Out of the 12 basic principles of animation, you most certainly know how to use the "appeal" on a character. For that, I thank and applaud you!