I just took a walk outside to test the running features for you.
The band took about 15-20 seconds to get a GPS lock, might be faster next time now that it knows my location. While you are in running mode it shows your duration, heart rate, and calories burned. If you swipe down you get a screen that shows GPS status, pace (instantaneous) and distance. This second screen stays for about 10 seconds or until you swipe back up. When you end the workout it shows you a screen with total distance, calories, and average pace, time, etc. It seemed to work pretty well, not as nice as my GPS running watch, but I think it will get the job done.
However I am still having problems with it staying locked onto my heart rate. It can only seem to hold a lock for a few seconds before losing it again. So it seems I am only getting a heart rate update every 30 seconds or so. I just got off the phone with Microsoft tech support and they were very helpful but ultimately unable to fix the issue.