Very accurate, no problems with finding and holding satellite signal. It is relatively intuative to use. Data screens are extremely customizable, which is very nice. Heart rate strap is very comfortable, moreso than others I have used. Software works well with windows XP, however on my new Vista laptop, I am having problems with connectivity (I have not taken the time to contact customer support, however). I purchaced the cadence sensor for the bike, which is working well, as well as the quick release bike mount and wrist strap for quick bike to run transitions. I find the strap more comfortable and stable than the wrist strap that came with the watch. I have just started using some of the training tools, which has been fairly easy so far.