Got my Nexus 6p on Friday. As background, I feel like battery life is *the* main thing that determines whether the phone is good or bad... and I am now convinced after a couple of days that the 6p has perfectly decent battery life. I am replacing a Sony Z3 Compact, which has outstanding battery life, and was afraid I would have to compromise with this phone. I don't. Yesterday, as an example, I took it off the charger at 5am, browsed on it, made several phone calls, listened to a couple of podcasts, played some puzzle games, etc... probably 3 or 4 hours of active use over a 17 hour period, and at bedtime I was at about 40%. This is more than acceptable and pretty similar to the Z3 compact.
One difference from other phones is that the real battery savings are when the phone is sitting idle. It always infuriated me that phones would leak 5 or 6% of battery life an hour just updating email and having background applications running. The 6p appears to 1% or so per hour, so you're not leaking battery during those idle times and you're saving the battery for when you need it.
So -- my non-expert verdict: The battery life is pretty decent, at least for me.