for my 640xl the battery life seams pretty good. i have 83% now from 6 hours ago's 93%. the battery saver is always on. And with wifi 4g on ( note, when wifi is on, the 4G will be off) and checked some emails, social networks, store update for some apps and so on. when i had the airplane mode on, the phone dropped about 3% overnight (from 22:00 to 8:00 this morning).
just the store apps update is way too slow. and sometime i get 1 sms notification on the glance screen even there is no new sms.
Plus, i did hard reset before upgrade to 10549, then another hard reset after completion of the 10549 update. then did another 'small phone update' . plus lots of apps update yesterday and today.