How much is left to change in mobile user interfaces and functionality? Not much, I say, but none of those functions mean anything if the device you use doesn't have power. Battery life is the last, great, competitive advantage to the moble manufacturer that gets it right.
Unfortunately, I don't think there is a battery life silver bullet. End users will see the most battery life through improvements in hardware and software.
Consequently, I think the most important part of any mobile announcement is, how does it benefit battery life? Here are some things to look for.
Google has just announced a new major version of Android, Android 5.0 Lollipop. Ever since the Google I/O conference earlier this year, Google had been referring to this as Android L. At that conference Google presented something they called Project Volta, which are the battery improvements in Lollipop. In upcoming weeks we will see reviews of Android 5.o, I recommend zeroing in on reviews of it on existing hardware like the "original" Moto X to see how it really improves battery life.
Apparently we all like smartphones with bigger screens, as every smartphone company is selling a phone with five inch screens and larger. What comes along with the larger phones is longer battery life, simply because they accommodate larger batteries.
If you want the iPhone that has the longest battery life, buy the iPhone 6 Plus. The trade off is not between how comfortable one phone is to hold over another, or how well one phone fits in a pocket over another, but that comfort versus longer battery life. If you want more battery life, get a bigger phone.
The other half to battery life is charging, and right now there are two emerging ideas on charging batteries. One idea is wireless charging, if all one has to do is place their phone on a pad to top it off, and the pads are readily available, it is more convenient to charge up your phone throughout the day, and the result is having a charged phone when you are out and about.
Another idea to improve battery charging is to shorten the time it takes to charge a battery. Imagine adding hours of battery life in a matter of minutes. Qualcomm's Quick Charge 2.0 technology is in the new Moto X, and Motorola claims you can add 8 hours to battery life in 15 minutes by using the Motorola Turbo Charger with the new Moto X. The phone and the charger have to support Qualcomm's technology.
If you are in the market for a new phone, I personally recommend looking at the battery life features I describe above. Even though I like a smaller phone, if I were buying an iPhone, I would buy the 6 Plus due to the longer battery life. If you are looking at Android phones, there are several large screen and bigger battery phones to choose from, but also look for support for Android 5.0 and either the Qualcomm Quick Charging technology or Qi wireless charging.