Having owned two Androids, a Nexus 7 and a Nexus 4, I have to say that the battery life on both is awful, just plain bad. I can maybe get two hours of screen time on the either one BUT if I barely use them, they can go for nearly two days on standby.
I've even gone to turning down the brightness to just about the lowest setting it can go at night and that doesn't seem to help to much.
I just don't see how Android can improve on battery life to where it's anywhere comparable to an iPad. I can use my iPad anywhere from 10-15 hrs before having to charge it and at least 6-8 of that is with the display on using apps.
Apple has truely done amazing things with these iPads enough to where you can have fun using it and be out the whole day and not worry about finding a plugin.
Maybe one day Android devices will be able to last as long as iPads do on battery power but so far, I have not heard of any that can. And don't go by what they say it will last, go by what people say it can last. That's what matters.