While I like that they have worked on finger print reader features (which I use and enjoy having on my computer) on Android M not many phones have finger print readers built into them at this time. Down the line more may, and it may become more useful, but for now the Doze power saving option is the one I expect to find most beneficial. The longer the battery lasts the longer the phone can go between charges. The less the phone is charged the longer the battery life span will be, and in turn the longer the phone's life span will be.