It's funny you say that it looks soft in the middle. I thought so to but no matter what I did it looks that way when I shoot it. Not sure if it's just the nature of those tips, they don't have any real detail, or if it was me but I noticed tht the spines sticking out are sharp at least the yellow part is. Maybe Sean will stop by and help me out.
I love the colors. Maybe it's my eyes but it seems a little soft towards the center. Certainly the purple petals around the outside are slightly OOF because of depth of field. There seems to be detail in the center that may not quite be coming out. Maybe some selective sharpening in that area?