Needless to say, I am quite impressed with the result. It seems like either Lollipop is really optimized for Nexus 6, or my coverage with AT&T has improved where the phone is not wasting battery trying to connect to the network all the time.
I do remember when I first received my NEXUS 5, I was impressed with the battery optimization (62% of power left after a full day of use); but few months later, things got weird and battery behavior became erratic (perhaps after an android update). I am hoping the NEXUS 6's performance will hod up longer.
(Screen capture of NEXUS 6 after approx. 60 hours or 2.5 days of use... still 7% left!!!)