I really love the concept and the feature , but it be very inaccurate when run near tree or in the city . I also have the Timex oem with the big arm strap Garmin GPS receiver and it be by far a better receiver and interpolate between low gp signal spot accuratley , but I have to wear 4 thing on my body to get same functionality and no download of datum . I find my self use the Timex anyway because it be more reliable . the 301 do not interpolate between point . the heart rate monitor frequently lose or have false high value , but not too bad . the description for the ForeRunner 305 say it have better reception , have anyone experience it or see a comparison ? be there a way to demo one to see if it work any better .