COMPOSITION A slightly unusual treatment in the composition because the flower dominates the frame and is centered, but you left a bit much space at the top. Generally, I think if you're going to fill the frame with your subject, you should go all the way and get in really close. If not, back off a bit and go for an uncentered comp, maybe using the rule of thirds - maybe not. You're subject is somewhere in between, but closer to a full macro. OK, so what of the macro? Nice detail in the inner part of the flower, beautiful color explosion, and the yellow petals are brilliant. I like the soft greens and blues in the background. As for the color contrast, yellow doesn't contrast strongly with green (blue is better), but your subject is vibrant and stands out nicely.
TECHNIQUE I think a slighter greater depth of field would have worked better, preserving the focus on the flower petals, while allowing the background to softly blur, as you have it. It's not bad at all as is, but might have been a little stronger if the petals had been sharp to the tips. The lighting is nice and bright, but the yellows are dulled a bit, especially around the bottom, by some shadows. I love the color saturation. All the colors are bright and eye-catching.
OVERALL IMPACT Generally, the impact of this photo is pretty high. In spite of what people say about flower shots, I think a good isolated flower is hard to resist. Your score of 5.5 is about average for a challenge shot. You may have squeezed a bit more voter satisfaction by a slightly different crop, but overall, I hope you are happy with your shot. It's quite a pleasing looker.
Fabulous color, very very nice focus. The composition seems a bit lacking with the flower nearly smack dab in the middle of the image, I have no suggestions on how to give it a bit more drama though. I think this is the kind of image that would be improved by having a simple but strong black border. It would give it a finished look in my opinion. I gave a 5
Okay... So this is what my flower shot was supposed to look like! Outstanding clarity, deep rich tones, heavy shadows, and beautiful presentation. What else can I say? (Wish mine was this good!)