Strengths: its reliable, its battery life is suitable for most runs.easy to use and read on the move
Weaknesses: Battery life to short for some ultra`s
Overall: A really usefull aid to training, the virtual partner is a great motivator when you wan`t to push yourself. But by the same token by setting your target time/ pace for a race then the forerunner comes into its own helping you to resist the urge to go off to quickly, and assisting to maintain an even pace throughout the race.
My forerunner is used all the time while training both on the Fells and road, then when i get home the forerunner is linked to the PC via its docking cradle, while i put the kettle on and have a shower,the training session is downloaded to my training log ready for me to apraise while drinking a nice hot cup of tea all without the need to lift a pen. I also use it in conjunction with Memory Map when recceing routes for Fell Races this the enables me to download the route i have run to a OS map and the look to see how my lines between checkpoints etc may be improved come race day,then when i am happy with the route the map can then be printed off for the race race.
I have never used the forerunner as a navitional tool and so i am not in a position to comment on that aspect of it. After 14 months of ownership the forerunner has become my favorite trainig partner