Note: The comments are given as part of the joining process of the "Give Me Feedback" group.
First off, the positive. I love the framing of that shot and the high contrast that is rendered by a good subject/background match. The yellow of the daffodil makes a stunning impact on a "purplish" background. The blur in the background is perfect and I don't notice any noise in it, it's very smooth and pleasing.
The thing I would try to make that picture even more stunning is to slightly increase the yellow saturation of the flower and, depending on what that change makes, maybe slightly increase the luminosity. I think a Hue/Saturation layer with a mask could do the trick here.
Lastly, and this is purely based on what effect you wanted to have on that picture, I wonder if a different aperture would not have been better, meaning that I would have preferred to have the entire flower in sharp focus while keeping the same amount of blur in the background. Then again, this is an artistic choice and might not be in accordance to what you wanted. I just wonder how the same shot would have look with a different D.o.F.
In conclusion, I really like that shot and in my opinion, it's the best one out of the entire series.