There is somewhat of a controversy about running with music. Some studies suggest that listening to music can make running feel easier, and it can break up the monotony of running on a treadmill during the winter months. Others argue that listening to music, especially while running outside, can be dangerous. Having headphones plugged inside your ears removes you from the sound of that dude creepin' up on you with a blade, cars whizzing down the road at top speed, and various bodily cues that provide feedback about running speed (e.g. breathing).
Personally, I never run with music. I find headphones uncomfortable and don't like exercising with any additional clothing or items on me. Also, I spend a good portion of my day outside of my body, e.g. absorbed in a book, in front of a computer, multi-tasking appointments, and surrounding by a lot of noise that I need to block out. The activities make me feel out of touch with my body. I find that running helps me reconnect with my body and helps me focus on my immediate physical environment. But, with that said, I do like listening to music before a big race, specifically 70 and 80s classic rock.
So, what do you think? To run or not to run with headphones?
FYI: Here are some informative articles on running with music from Runner's World: Running w/ Music.