How did Windows 8 affect your laptops battery life?

So. Windows 8 is supposed to be more efficient and lower power than Windows 7, but how much of that actually translates to real life after everything else is taken into account?

I use a Thinkpad X220. 9 cell battery. After upgrading to 8, I lost about 1 hr of battery. I usually got ~10hr with it, so -1hr loss isn't much, ~10% or so, but it would have been nice to gain battery life instead of losing it. Hopefully it will get better when Lenovo releases more finished power management drivers for Win 8.