I believe, as I mentioned in my original comment, that this is a very appealing photo. The most striking part of it for me is the nice mesh between the purple and yellow color on the flower petals. The yellow center really pops out nicely against the purple surroundings.
I also prefer dark backgrounds on most flower shots. It does a wonderful job of isolating the flower from an environment that could otherwise be distracting in various ways.
One of the compositional elements I particularly enjoy in this image is the way the upper rear petals seem to form 'wings' for this flower. That element almost gives the front facing elements of the flower some facial characteristics... maybe a purple angel in flight :)
The image is slightly grainy... probably a result of the ISO 400 camera setting. I believe the color saturation could be a little better and the grain removed completely by shooting at ISO 100 with a longer shutter speed. A tripod would be required and some patience to set up the composition, but I think it would enhance the overall quality of this image quite a bit :)
Snap dragons are great! Pity there wasn't more of them behind it as this (to me) is what flora is about. Did you light this? If so good job. Really bought the highlights out.
It looks like you tried to crop much too tightly on this photo... it looks really grainy to me. Also for deep purple I think I would have liked maybe a little more color. Good composition though...