I am willing to bet most of these "low battery capacity" claims are due to user configuration issues. iOS has gotten quite complex, and typically are configuration based --- such as the above poster not understanding that iCloud would drain battery during the first uploads to the cloud of data.
It seems to work fine for some people and awful for others. It's quite perplexing.
It's definitely something that can be corrected with an update, I just wish Apple would acknowledge it and let us know they are working on an update.
People shouldn't have to turn off all the features that make the iPhone great just to get a half-decent battery life. If you can't use what makes the iPhone great, might as well go to a different device.