Dr. Drang did some iPhone battery calculations and concludes as follows in The small improvement in iPhone battery capacity:

It’s no secret that Apple has taken pains to make iPhones more and more stingy with power. What I didn’t appreciate until I put this table together was that the ability to still get a day of use out of an iPhone is due almost entirely to improvements in all the non-battery hardware and the software that drives it.

There have been a lot of complaints about battery life under iOS 7 — myself included:

7.0.1 please come soon to make my battery last past noon

— Rian van der Merwe (@RianVDM) September 22, 2013

There has also been a slew of articles on how to improve battery life under iOS 7, the most helpful being The Huffington Post with 9 Ways To Improve iOS 7’s Battery Life. Although some might argue that this advice from Yahoo! is the best solution:

That said, Dr. Drang’s points are interesting, and his article is well worth reading. It seems that improving software is an easier way to improve battery life than changing the actual hardware is. But I do hope we see some hardware improvements soon, too, because it’s really starting to cripple the phone. If you have to turn off essential features just to make it through the day, something is not right.