I quite like the BG, although I accept it won't be to everyones taste. The open mouth is great and you've got the whites just about perfect, good stuff
I like the tight composition, eye ring, BG, sharpness and details. I see an area on the gulls back that has the same color as the BG and a dust spot in front of the upper part of the beak near the frames edge. Very well done Karl!
Great pose, colors, comp. Although the exposure looks just right, the top of the head is lacking detail. Given how close you were to the bird, you needed to stop down considerably to get the necessary DOF.