Strengths: 1. Downloading and reviewing the data. 2. Heart rate monitor.
Weaknesses: I haven't had it that long and suppose I agree a little with the fiddly buttons on other reviews, but I've only pressed the wrong button once by mistake in the 1st month of almost daily constant use
Overall: I've previously had 2 other types of GPS system, an Ironman watch and a Navman, and I think this outshines the pair of them, especially the Navman which I found fiddly with only 2 buttons.