The yellow wash makes the text in that area difficult to see. The concept is really great, and it could look fantastic.

I have to say, though, I think you should actually shell out to have a real commercial artist do the finished piece--it's 100% obvious that this is hand-drawn art, and as such, it's not going to be as versatile in the long run. Do you want a piece you can eventually put on a big sign? On a t-shirt? If so, hand-drawn is probably not going to work.