There's something I love about the somewhat crayon-like feel to the texture in this. I love the way you depicted Chell. The feeling of movement in this picture is brilliant and your perspective is spot on.
And the boots. Oh. My. GOODNESS the BOOTS. They are PERFECT.
Nice depiction of the cast. I'm not sure what you used for the lines, but I love it. Everything looks a bit gritty. Chell's pose and anatomy are pretty spot on. The composition is really cool and definitely not something you see every day.
The big font "2" to the side sort of throws me off when the whole feel of this is off-kilter and hand drawn/painted and then - BAM! - sudden, not-so-hand-drawn number floating there. I think it would be improved if that had been done by hand too, or at least filtered with some texture so it isn't so abrupt. *ker-FAVE'D*