I like how the graininess adds to the 'softness' of the photo, though i find that the angle of the branch seems to sorta push the flower head down, giving the whole picture a bit of a 'sad' or 'weighed down' look.
high key images are hard with grain. Natural film grain is less apparent in whites, and in that, I think you mimic it well. I was going to ask what the grain was adding, but I think it does add texture. It doesn't enhance a mood, but works as a visual device. Too bad this isn't in the light-on-white challenge.