I love the vibrancy of the blue in this piece. I think one of the things I would have liked to see would have been for the back ground to have been a little more developed. I love the suggestion of trees that is indicated blue lines and I think adding some more would have given the picture greater depth. With that idea is the fact the leaves are very present and detailed on the black forward branches yet don't appear on the branches in the background. The only other suggestion I would make is to think about the negative spaces you're creating. There's a lot of drama in the piece especially with the lovely contrast you have going on. Looking at the shaping would create more eye movement across the page. Overall the piece is a really good concept and with a little fore planning would be even better than it already is.