I would take it with Flash around f/4.5 and ISO around 100 & Expousure Comp. (bias) at 0 with the flash, lighting front or to the side some. ISO 800 and a shutter speed of 1/25 results in not so sharp focus and invites noise. (maybe not so much on a 7D, but with good light...why ISO 800 and a 1/25th SS?)
I like it. I might subtley burn the LL and LR corners. Also, there are two hairs on the left of the stem, against a purple BG, that I'd retouch out. I like the backlighting and that fact that the stem, not the flower, is the subject.
