As you can see, nearly 22 hours so far on 65% battery life. I will let you know, I turned it on at 100% to test using the basic features. I can tell you, they are nice to have. Texts, calls, voicemail, email, calendar, and calculator. You can also have functionality with your lock screen widgets too, which was a surprise. You cannot go to the home screen, use the web browser, and your motion controls are disabled, as well as your background data.
Want to know how to go into your main phone settings? You know you can, and here's the only loop hole I found. Press on the Dialer App, then press the menu icon (three vertical dots), then tap settings. Now, you will notice you are only in call settings, yes, BUT you are now close to pressing only one button to open the door. See the word, 'call' up top, and the back arrow....press it. Poof! Settings. Now from here, you still cannot go to the home screen. Keep in mind, with some settings turned off, by the new battery mode, you might get some force close errors. Ie, trying to change the wallpaper on the home screen. You'll notice certain features are disabled in settings, so as not to disturb the battery mode's current job on saving you battery.
Have fun!