Very nice. White flowers seem so hard to photograph well. You've managed to get the perfect exposure, focus, and the subtle greens really add to the photo.
That one petal that is twisted on the left breaks up the purity of the subject somewhat. I might have been tempted to just clone that out right at the twist part.
Pretty, but the petals of the lilies lack the detail they need to really give them oomph. Maybe the lighting, maybe the lens. I have the exact same problem when I take images of white flowers. I like the black background. I think I would have prefered more neg. space to one side as well.
The translucency of the petals is well caught, but i think your lighting overall will let this down - there just isn't enough perceptible detail in the flowers. Difficult to light properly this, anyhow - but absolutely crucial to the effect that it should be.