I charged mine fully last Thursday just after I received it. I've been playing with it loads, activity tracking enabled, bluetooth'ed to my phone for notifications sync etc, admittedly only an hour of GPS activity (too busy at work and been away) but I'm still on 70% charge. Can't complain at all.
71% since Monday @ 2pm with 1 hour 5 minutes of running, so far, with smart notifications, enabled, and 50% backlight.
I'm planning on letting it go until 0% to get a general idea for battery life.