How Music Affects Your Productivity by Gregory Ciotti is a fantastic article on all this. It's changed how much I use music when

“When a task is clearly defined and repetitive in nature, research suggests that music is consistently helpful.”

But he goes on to explain that it can be more distracting when you are working on creative tasks. In this situation familiar music works best as it doesn't surprise us as much and interrupt flow.

“Whether deliberately created or naturally occurring, a soft background noise is what you should aim for.”