Day One: With 6 hours of heavy use it was at 22% (right out of the box without being fully charged)
Day two: 12 hours heavy use (15%)
Day three: 13 hours with heavy use (15%)
Day four: 13 hours with heavy use (22%)
I'm sensing a strange pattern here.
My rundown of Heavy Use: GPS ON, Mobile Data On, WiFi On, Strava or workout app on for extended periods of time while streaming Google Music, Pandora, or Soundcloud. Messaging, Google Talk, Visiting multiple social networks in succession in quick burst (5-10 minutes each). 2-5 phone calls ranging from speaker phone or headset (5 minutes each). Google Search.