Received the phone yesterday, and restore my apps and charged the phone to 100%. Taken the phone off the charger before went to bed with stamina mode on.
Throughout the day, browsed news, watched and listened podcasts while downloaded some large size games on WIFI.
As you can see, about 15hr and 45mins with 5% left is very good result. Consider the phone was actively used for 10hrs and with screen on time of 6hrs 30 mins.
This is a phone can easily last one full day of heavy use without problems. It is hard to imagine another similar size phone with same house power can last from 8am to 12am with 10 hrs of active use and 6 1/2 hrs screen on time.
Hopefully it will get better after few more charge circles.