I think this is just about perfect! I love the way it is positioned, it really brings an effect. Maybe you could brighten it or darken the edges around it. I feel that would look cool, but I don't know.
Very, very pretty picture- it looks really professional! I hope you know that your work is all great, I was looking throughout it all. When I saw this picture- two words came into my head. "WOW, pretty" I've seen good flower pics before, but this one is near perfection Love it. There isn't much more to critique, because it's so amazing. The one thing would just be like brighten it or something like that. Thanks!