It is a nice shot. Some times when you cut the head off of the reflection it is best to crop it close, so it does not fight the bird. I tried a few tricks to improve the picture but the only thing that made a good change was the top slider in curves, other wise your right on. I had the 100-400, a good len but finicky. You shot at F8 so the DOF is good. I found the if I tripod mouted it and took Ed Prete's suggestion and get the Wimberly side kick my sharpness improved. The are some experts here who might help better.
You know that I'd be the first to say, "I'd like to see a lower angle"... but; I think the angle works for this image (considering the inclusion of the reflection). I just wish there were more eye contact (involvement) with your subject. Also, keeping the full reflection would be nice (placing the subject higher in the frame would accomplish this). Overall, well captured. Keep up the good work.
Thanks for the all the feedback. My self-critique is largely around cutting off a bit of the reflection. Despite 4-5 images of this bird, none captured the whole reflection, and each has it's own short-comings.