Strengths: More accurate than using the car or bike to measure distance and can go anywhere. More functions than most will use. The ability to bring up run or race info in seconds from months ago. Multi sport use helps categorize data. Saves hours of calculator work.
Weaknesses: Not accurate enough to pace a race by. Can be more than a mile out over a marathon. Can't always cope with tall buildings and tree cover. Time lag between action and reading given too long. Heart rate monitor can lose signal for no obvious reason. Graphs aren't easily saved, printed or shared, which rather negates the whole point.
Overall: Not perfect but a very big step along the way. Improvements in accuracy will be welcome as well as more functionality in the software. The ability to overlay workouts and see time, distance, pace, heartrate and elevation data simultaneously in one window would be useful.