Got my watch a few weeks ago and since then have been pool swimming (up to 2 hours), running (up to 2 hours with GPS), biking (up to 4hrs with GPS), triathlon(ing) (Ironman distance 12hrs) and hiking (2 days with GPS on for approx 8hrs) with it. Also, I have been wearing it day to day as a watch (for time reading purposes).
I find that the battery is good for all the activities listed above, I still want to see how long the battery will last and whether it will last over a 4-6 day hike (using GPS), but my first impression is that its great. Its awesome that it easily syncs with my phone and other apps (i.e. Strava). I got the sapphire version and its great that it doesn't scratch (however, the metal ring around the face does scratch).
The strap is comfortable and the face can light up which is great when swimming in murky water (or if its dark obviously). Also its awesome that the GPS connects really quickly to satellites (within 30sec at most).
Great buy, would definitely recommend to anyone who wants to track their activities.