The bird seems sharp, but being so small in the frame limits its detail and therefore impact. The BG is nice and the perch is interesting, but the out of focus vegetation in the foreground is a negative. (If it were much closer to the camera and therefore much more OOF it might be an artistic touch.)
Getting closer probably wasn't an option without frightening the bird. This is a frustrating hobby. And often requires hip waders and a lot of patience.
Beautiful bird and environment. Immediately when I saw the photograph, I thought, "Oh God I love this photograph." Especially the composition. Diane's right, of course, about the soft focus of the foreground vegetation. I wouldn't know how to balance things. With that lens and TC combination, the DOF is going to be thin. So. How to create this, for me, enticing composition and get appropriate DOF? I don't know. This might just be an image where the viewer accepts the limitations for the overall pleasure of seeing the bird in its habitat.