First off, the deep blues really compliment the rich purple hues beautifully. Each petal of the rose is nicely defined, and the blurring around the edges draws attention to the center. What may improve this, is capturing more of the rose, or a slightly different angle, or a portrait shot instead of a landscape. A simple black border might bring out the color and do more to draw attention inward as well. A rose is definately a good choice for a flower to capture because of the way light hits the surface with all it's nooks and crannies, and mixes with the shadows creates some beautiful effects.