This is a Chrysanthemum. One thing I particularly like about this flower is how at the base of the petals, the edges of the petals fold in. This is caught very nicely in this picture. Also, the base of the petals have a slight yellow-green tinge, which - I'm guessing - is due to the green colour of the centre of the flower. The focus on the petals at the far end of the flower is very nice, the focus on the petals nearer to the camera is a fair bit more blurry, which is good, but I would say it's the slightest bit too blurry. I really like the background in this picture, it makes big contrast with the Chrysanthemum in the centre of the shot. It's a very dark, sort of forest-like background, it's rich and a very nice contrast with the central flower, except for a couple of other Chrysanthemums that are just opening.
