I'm unsure of why so many people bang on Android (as a whole) being so terrible on battery life. To say that companies who throw these skins on the phones are what kill it are somewhat true, but at the same time Rosie.apk (HTC's Sense GUI) has been a pig for the most part over the years, but has become more and more streamlined with every iteration of Sense, up to it's most current (and absolutely beautiful) version, Zoe.

Hopefully this will be near the end of the road as far as in-your-face designs, as most companies are now going quite light on the themeing of the OS. TouchWiz is likely the most in-depth at this point, and we don't know what's going to be on the SGS4. Hopefully it still retains decent battery life, as I'd routinely get 36+ hours on mine when I had it.

Heck, I've recently upgraded my SGS3 to a Nexus 4 and am currently doing a rundown test. Below are my current stats running PAOSP and a stock 4.2.2 kernel with all 4 cores activated and no crazy governors, undervolting or underclocking. If you can't see the image, my widget on screen shows 22.5 hours of uptime with 69% battery left. I'd say that's pretty decent battery life.