Don't do it.
My battery life is garbage now. I take it off the charger at 7am and by 5pm, with only checking the time every hour or so, it's at 20%. And that's without wifi, since you know, I can't even turn it on. Have had the grayed out wifi button glitch for 5 weeks now. 2 updates and they haven't even attempted to fix this problem. Unbelievable.
Don't update.