To which extent peer feedback can affect the quality of a music composition? How does musical experience influence the quality of a feedback during the song composition process? To answer these questions we designed and conducted an experiment in which participants compose short songs using an online lead sheet editor, are given the possibility to feedback on other participant's songs and can either accept or reject feedback on their compositions. This experiment aims at collecting quantitative data relating the intrinsic quality of songs (estimated by peer evaluation) with the nature of feedback. Preliminary results show that peer feedback can indeed improve both the quality of a song composition and the composer' satisfaction about it. Also, composers tend to prefer compositions from other musicians with similar musical experience level.