Lovely! Wonderful interplay of sharp details in the butterfly, repeating diagonal stems and soft OOF bkgd. I really like that the upper flowers & stem are in sharp focus and the direction of the flowers are towards the butterfly, gently keeping your eye in the center of the image. Some might comment on the butterfly being behind a stem, but I like the overall composition and that the stem & flowers bend gracefully with the butterfly. Maybe tone down the brightest highlights in the bkgd some, and see how that looks.
Stuart the butterfly couldn't be much better, in fact it is so strong that I am tempted to ignore the background and the stem in front of it....but I can't, to my eye, they compete too strongly for attention. Your flash setting appears to be excellent as does the plane of focus.