It's definitely a 4.3V chemistry. Running on the charger I see 4.29V using Battery Monitor Widget after the JSS15Q update. Before the update I regularly saw 4.30V. Google may have decreased the max charge voltage slightly trading off a little capacity for a little longer battery lifespan.
I've been very surprised how seldom it gets mentioned. Even the big name reviewers seem to have missed it.
I suspect that the actual battery capacity in Watt-Hours has stayed the same or gone up slightly compared to the 2012 N7 even though the quoted capacity in Amp-Hours (mAH/1000) went down. Most folks don't seem to realize that mAH is a meaningless number for comparisons unless the voltage under load is identical.