I'm really curious about battery life when using the GPS. I have a really lightweight Garmin 220 and it gets about 8 hours of activity before the battery dies. Also, does the GPS only get turned on during certain events, such as when you start a run on your watch, or start doing a hike with an app (as they showed during the keynote). They said 3rd parties will be able to use the GPS. I'll be ordering one on Friday.