I followed the instructions to manually update to 12070 yesterday and everything went smoothly.

I've only had the Lumia 800 for about 4 days which so far equals 3 full discharges. Yesterday, before I updated I made a mental note of the usage; full charge before sleep I unplugged it and after just under 17 hrs I was at 44%. Today with the new firmware, approx. the same usage time I have 62%.

I contribute both battery conditioning and mainly the firmware for the increase. On new devices I always fully discharge and recharge 4 times. Then plug in when needed. Once a month or 2 I'll repeat. Seems to work for me in keeping the battery at it's max. potential.

Either way the 800 is better than any Android I've owned (3) and Blackberry (briefly a 9790).