Strengths: ...wearing it in the car "are you sure officer, my Garmin 305 says I was only averaging 69mph!" (Avoid mentioning the 5 minutes at max hr when he was in pursuit!) Is your Marathon training frustrated by a custodial sentence? - Gain weekend release for those long runs "don't worry you can track me on my Garmin 305!"
Weaknesses: Don't buy if...your "Sunday 15miler" is actually a 3 miler to the pub, 2 pints, and a womble home to your other half pretending to be worn out - you're exposed through gps and google maps! Or if you are the one using Thursday"intervals" as a cover for a passionate weekly liason with the wife's sister - it'll be no good showing off yout heart rate printout if she has hold of your grid coordinates!
Overall: Why not buy one as a "peace offering" for your arch racing rival, then simply employ a teenager to hack in to their computer - all you'll ever need to know about their training schedule, biometrics, and the truth about that extra run they claim to do each week! And on the subject of buying for others, an admission that the sole intention of this "review" is to get those lovely people at RW to send me a freebie Garmin 305 - who knows I may even be able to put some of the suggestions above to the test for real and update you in a genuine review, and with the money saved I'll even take out a subscription to RW!!