the dof is too shallow i think, with some of the branches not being in focus, and the sky is really blown out with some purple halos around the tree in that area. Also, I dont think the fills the frame.
nice use of a shallow depth of field to bring out your subject. probably the biggest problem with the picture, is the purple fringing. it's unfortunate that many digital cameras suffer from this. however, you could have controled it by possibly recomposing the shot in such a way that you could avoid placing the branches over the sky.