Pros-Excellent device. Always you to run anywhere while tracking miles, time, and heart rate. No longer constrained to known tracks.Cons-First one failed/returned. Some of the features like pacing and calories do not work well; the sample period is too short so it wonders to much to be useful. Elevation tracking is poor (+/-30ft, cycles up/down, known GPS issue), so calory estimations are way off.Even with flaws, wonderful device for monitoring your training progress... love it.