This is a wonderful example of a classic still life shot.
Composition: I love the arrangement of the roses here. I think that having some in the background is a great idea. I also like the color of roses you have chosen.
Focus: Your use of a very narrow depth of field is a good idea - the background roses are very well blurred. My only gripe here would be that the plane of focus is just a little bit in front of the main rose in the shot. I think that caused you to over-sharpen just a little. If the front edge of your main subject were in perfect focus, then the narrow depth of field would be perfect.
Lighting: The bottom of your shot is perhaps a little bit dark. Maybe a reflector or a small light coming up from underneath would fill in those shadows just a little, without ruining the mood created by the dark areas.
Good work! I hope to see more of your work in the future.
I love the soft pastels but while I like the backlighting, I find it to be too strong so that the background roses are too washed out and merge and detract from the main rose. I also think some fill light could have been used to illuminate the bottom of the photo more to show the greens of the stems better. Good DOF.
Depth of field is perfect. i would have like to have seen a little more of the rose to the left, and the dark pink rose blurred in the background is a little distracting.
Love the softness this photo sets off. The pink is fab. I usually see roses (flowers) in vases for "still life" stuff, but I'm glad you choose to do a close up. Very nice. 10 from me =)