The interface went from intuitive to annoying (even the dedicated polar activity button doesn't work unless your already start the polar app, which at that point defeats the purpose of the button, and swiping, which used to change between apps now changes the watch face, it's annoying as hell).Aside from that, but it crashes more

However, the heart rate monitor as spotty at best, and the sleep monitor function is next to worthless as it reads sitting and reading or watching TV as sleeping and provides.