I wish there was a bit more light on the far left side so you could see a bit more of the red petal as it fades into the darkness. I like the play of light over the top red petal, and think that the same effect to the left would be nice. I suspect that would require multiple flashes, or perhaps some form of reflector.
The other thought is that I might consider dimming the background leaves just a bit, so they don't compete with the foreground quite so much. Its very close, but just a bit more brightness separation might really help the flower pop.
I don't have much experience in the macro world, but just my observations for you :)
Bruce, I agree with Randy...bringing up the shadows on the left side leaf just a bit more and maybe a tad more right at the central point of the flower would really give this even more drama. Right now it feels a tiny bit underexposed but yet you can tell it's not...it's just that the mind wants to see a little bit more of the action!
Before I read the comments I was analyzing the image myself. Randy covered the comments I was going to make very well. As was stated about more light on the left and a less competing backround. I would also add a bit more room on the bottom. Your subject matter is great and existing lighting is pleasing.