For serious experiments I do run with an iPhone strapped to the hard part of my hip with a modified armband. So far using Runmeter app I can do two things:
Collect quite a number of channels of data (pace, HR, elevation, etc) from any devices that can bluetooth to Runmeter.
Get once per minute audio updates on any of those primary channels or even time averaged pace, total distance, average HR, etc. This is a huge help when trying to hold pace, or hold heartrate, or hold average pace over hills, etc etc. No looking down at the wrist.
I listen to the audio annunciator through a bluetooth earpiece that I pin to my cap, visor, or winter hat (not in the ear).
At some point in the future I believe rS will have the ability to transmit at least some data real time, and I look forward to running while getting real time feedback. Example: % flight time, I can see some very positive stretches of high flight times in graphs of my outdoor runs, but for the life of me I've never been able to correlate those peaks to anything I remember doing after the run.
Never listen to music.