Strengths: The Heart Rate monitor features have never given me a moments trouble. As soon as you start the monitor the heart rate registers within a few seconds. I've never lost a HR signal in all the time i've been wearing it. The battery life of both the watch and HR strap are superb. I've used the HR strap for 18 months with only 1 battery change, thats running average 3 times a week. You can set alarms for the different HR training zones if you wish, personally I find this a constant alarms a touch annoying when I drift a BPM or two outside the target zone, especially on a hill.
Weaknesses: The GPS unit has shrunk considerably compared to the previous model. However, the previous model was far more reliable, locked into satellites in less than a minute and only lost signal in very heavy cover. As soon as this version was released I bought it because 1) It takes less batteries but still has a respectable battery life. 2) It's much less bulkier and lighter.
However, it just doesn't perform, and I'll often use the old GPS unit instead if I know I will be running in woods, or around tall buildings.
I also have the data recorder component, to download the information to my PC. The software does an adequate job, but it is pretty uninspiring. I've also had numerous problems with the data recorder turning itself off half way through a run. It is supposed to have a 99 hour memory, but I find that unless I clear the memory manually often, it will switch itself off as mentioned.
Also, this GPS version does not 'do hills'. You have to buy the more expensive Trail Runner 3D watch to accurately measure your distances when runnig up and down hills...
Overall: I can't really fault the watch features. Usual stop watch, lap timers. I'd have liked to see an Interval training feature though. The HRM is excellent. If you are just after HR and watch, I'd say go and buy it. However when you factor in the GPS's poor performance, and the tempramental data recorder it fails to get my vote.