Interesting seeing what others are getting.
I've had the G4 for 3 days, after coming from the Sony Z3 (which had incredible battery life). Obviously the first day is a write off, configuring, uploading photo's to Google, downloading apps. This is my first 'proper' day, as it' a normal working one. I came off the charger at 7.20am, and have listened to music 1hr to work, bit of FB/Twitter, 2 short calls, few texts, bit of browsing - so far down to 74%, which will give me just over 19hrs at that rate.
I'm actually pretty pleased with that. On the Z3 I would usually be at around 80% by now, but the Z3 is the exception to the rule. I had the G3 before that, and changed due to the poor battery (I was charging again at 5pm, down to 10-20%).