I sure wish I could see a REAL yellow flower growing about now - My yard is still covered in snow and it is bitter cold. This is a nice cheery photo.
Yep, the flower is yellow, it meets the challenge, that part was easy.
You have used a very narrow depth of field which is effective for the background but have you missed the sharpest focus point? It seems to me to be on one of the green leaves, and I would prefer it to be at the center of the flower where it is all fuzzy.
Your composition is simple and classic. Very nice. Rule of thirds placement, foreground in focus, background out of focus. I like the way the main flower is mirrored by the back up flower in color and shape and orientation. The stem makes an interesting short leading line right up to the flower.
But there are flaws in the photo. First it seems a little flat. Besides color (which id very good), there isn't anything that stands out - no light, shadows, other intersting shapes. Also there are detractions. The leaf in the very front appears torn but may just be folded. the leaves look dirty. Whatever the grey/brown area in the background is, it is neither attractive nor interesting.
How would I have made the photo better ?(well, I probably wouldn't have to tell the truth already it is better than I can do, but I can imagine that I could have), Fill in the background with greenery so the out of focus area is mostly greens. Perhaps a splash of sunlight? Perhaps a splash of water? That would clean up the leaves and maybe some droplets would add the spark that is missing. Could you entice a lady bug into the scene?
Please remember that this is just my opinion and I an NOT an expert.
A well composed shot with the flower in the lower left third. I wish we had flowers blooming here in chilly, rainy Utah! Your most interesting light is found on the leaves to the right of the flower and on the leaf under the flower. Perhaps in a few minutes, the light may have shifted to the flower itself, or somehow set off the flower to its best advantage, but a nice shot.
I really think you should have croped the top below the upper flower, the one in the background. It distracts from the really neat flower in the fore ground.