Roses are always nice subjects - this one was not the best to pick, though, because of its wilting petals.
As for the image itself, Miguel's basically said it, but I'd wager that an ND filter wouldn't have solved the problem, since the harsh sunlight creates far too much contrast for the dynamic range of the camera to be able to render effectively.
It's all about controlling the light and creating a quality of light that is flattering - harsh directional light doesn't do this in most situations, and this is one where it makes the result just look like a snapshot.
You attempted to get a decent composition and control of background, but the result here is that the background is still harsh, due to the hard lighting, not complementary and uninteresting. This would deserve another shoot in more cloudy conditions or the use of a diffuser like a shoot-through umbrella to soften the sunlight and a reflector or barrier to cast a shadow behind the subject to eliminate the harsh background and focus the light on the subject matter.
Just some ideas...