while I often work out in the gym use a treadmile I do occasionally run outdoors and I will do more outdoors as the weather in mn improve as we move into spring and summer . what I really like about the 305 be its ability to track what I do outdoors use the gp -lrb- location \/ distance \/ heart rate -rrb- , and indoors on the treadmill use use the foot pod -lrb- purchase separately -rrb- and then upload the datum to my pc so that I can track my progress -lrb- and for the outdoor run see on a map where I go -rrb- . it be very encouraging as I lose weigh and gain stamen to actually see how my heart rate be now lower with higher level of exercise , and how my average speed be increase as well . I also like be able to always monitor my heart rate - which while I be run outdoors be important for I to know as I do not want to exceed the maximum rate for my age -lrb- and before I get this unit I be not sure how close I be get -rrb- . so the combination of all these thing make this a winner for I . the only downside I have find so far be that I would rather see my speed in MPH vs. my pace in min\/mile but that be pretty minor . also you can not display map on the 305 , just show the track of where you have be . I be not expect to be able to load map so this be not a take away for I , I just want to mention this for other potential buyer .