The composition is good and shows off both the curves of the guitar and the lines of the strings, with the rose as an added interest - also goes with the romantic spanish/acoustic guitar. Only suggestion would have been to have a light on the left hand side or something to bounce the light back to fill in the dark area on the strings made from the rose shadow.
Great. This is my favorite guitar picture. Very well done. Lighting the strings with a flash or somthing may have brought them out a little more (like they are at the very top)