I think its great. The saturation looks perfect to me, and I don't think it needs a border due to the black around the edge. The one thing that I do notice is that the background isn't actually black, it's grey, so I think you need to adjust the levels a little until the background is #000000. This will help the rose to stand out more.
Looks great to me. The contrast looks good. The color is highlighted with the overall darkness of the picture, so the desired effect of drawing your viewers' eye to your subject works great. I might crop a little more off the right and left sides just to emphasize this effect, keep the eye from wondering over to these edges to investigate. But it looks really good. Nice job. Of course there are differences in opinions and taste!