Should You Listen To Music While You Work?

Does listening to music while you work help or distract you?
According to a study done by Popular Science, it depends.
In their research, people who listened to no music or simple music (defined as having few instruments and little melody change) got the job done well on easy tasks. People that listened to complex music (more instruments, more changes) performed easier tasks even better.
When it came to harder activities, people who listened to music performed worse than those who listened to nothing at all.
Do you listen to music at work? Does it help you focus? Is it background?