although a little bulky on the wrist , this device log you location accord to GPS and heart rate from the chest transmitter , during you training and allow you to upload it to a pc for further analysis . this be probably the feature I find most useful as it allow you to monitor you improvement -lrb- or otherwise -rrb- over time by compare the result of you training session . I personally do not find the display too useful and tend not need to look at it during training as there be far too much information on it to take in , although I understand that it be possible to reduce\/customise this . if Garmin could reduce the size of the device by take the display off altogether , it would be great ... the only other dislike be that the hear rate monitor transmitter be a little bulky and be not compatible with most standard gym equipment , which be annoying , however as the watch be log all the datum anyway , it be not too bad . the time take to lock onto the satelite from switch the device on be a bit variable , sometimes connect in seconds and other time upto 5 minute . I could understand this behavior if I be turn it on in a very different location to where I turn it off , but I always turn the device on and off outside my house ... all in all , a very useful gadget .