I havent installed it yet.. but it is worth noting..
wondering if anyone on the forum has had the issue.

OS X Mountain Lion users reporting laptop battery life issues (http://forums.appleinsider.com/t/151727/os-x-mountain-lion-users-reporting-laptop-battery-life-issues)

i rarely use my battery but have heard from easily 10+ people that they are suffering from this

same thing happened from 10.6 to 10.7 FWIW