When i first saw this image the thing that struck me most were the vibrant colors.
Upon further inspection the bottom of the flower is a little bit out of focus, and thus detracts from the photo a little (i'm not sure if this is because of the dimmensions of the picture (height only 543 pix)and your file size seems a little small... make sure that your quality when you save is at the right setting). Another point to make is the lighting which you used. Using lighting to enhance a photograph is one of the most important asspects of photography and you used it well here. Creating a picture where the flower is somewhat transparent but not totally.
Overall the sharpness of this picture really makes it what it is. Another interesting aspect is the point of view. Most photographers would think to take this picture from the top of the flower, but you used a unique view.
An excellent photo which fits the challenge.