Well, depends on the type of person you are. If you like slow music and will not listen to anything BUT slow music, your running probably would not improve much. On the other hand, if you only listen to crazy fast music, you would tired out very quickly if you try to move your legs to that tempo. You should find music that matches your pace, if you like music that is.
For me, music is a distraction from the pain of my muscles. Although, when I do feel like singing it out loud, I find that it troubles my breathing, which makes me tire quickly. No, I do not like that when it happens.
If you are wondering whether you should try running with music or not, just try it at some sort of practice, or when you're running by yourself. Don't try it at a race, because you don't want to worsen your time if it doesn't work. I realized that it is easy to run with a partner too, so if you're trying to improve your running, grab a running buddy who's about the same pace as you!