It's pretty awful in the stock configuration, at least unless you disable LTE (in which case why did you buy an LTE phone?) or root it and use SetCPU.

Honestly, it's BS that you need to either root the device or disable its flagship feature to get acceptable battery life out of it. It's annoying enough that depending on what the new iPhone looks like, I'm tempted to bite the bullet and pay full price for it since I'm not eligible for an upgrade.