I'm into a couple weeks now on the Garmin 620 with the heart monitor and really liking it. It is helping me learn how and when to push myself or back off other than how just how I feel. The mapping features, stats are good guide tools for running the hills on my 10.5 hill runs. It's probaly not somthing you need to have but the analyitical part of me likes seeing my progress and breakdown on my progress. It keeps a running log for me without my writing a thing and uploads wireless automaticly to my computer or mobile device. I'm going to test it out running intervals. Seems like a good tool so far for what I wanted.