Today my fifth full day with my new Nexus 4, like I said been getting pretty darn good battery life each day, around 15 hours total battery life and 5h On Screen time.
Well was surprised to see the red alert battery life go off at 5:00pm today, unplugged off the charge at 7:00am. This was the first time the battery light went off so early in the day, the past four days, it was good until 10:00pm.
I know I used the phone a crazy amount today, was on it non stop, tons of phone calls, million texts, lots of e-mails, and surf the web quite a bit today too. I checked the usage just now, and my On Screen time was at 5h 30m already

Total time off charger 10h 20m.
So basically the Nexus 4 for me, tops out around a little more than 5h On Screen time, before going to red alert. That is still much better than my previous Galaxy Nexus, and little better than my old international HTC One X. Not too bad to get 10.5 hours total usage on a very heavy workday.