have been running version 4 of beta since it was released (bc it solves the dead when fully charged issue); thought i wasnt getting great battery life; yesterday decided to test, ran a 1030p movie, and used 15% for 2 hours (roughly 13.3hrs extrapolated) wifi on, no bluetooth or smart cover, 50% brightness.
this morn got pretty similar results but had my Air 2 running side by side, and had the exact same percentages on both, with same parameters above.
so pretty good overall I'd say on the battery, now the trick is to not think about it and look at the percentages constantly