I use my iPhone 6 Plus a LOT especially now that my laptop is in the shop and I don't have an iPad. I'm constantly browsing in Safari, streaming video from Hulu, Netflix, CBS, or YouTube, or on long phone calls (seems I'm one of the few people who uses the "Phone" in iPhone) and I always use it as a Music player with my EarPods and I got about 9 solid hours of usage, and 12 hours of "Standby" (which includes the aforementioned 9 hours) with the display around 50-75% brightness today.
I think it's amazing. I never used my 5s as much as I do my 6 Plus and I'd be lucky to get 6-7 hours out of my 5s. I do a LOT more with my 6 Plus then my 5s and I get a minimum of 9 hours. (Reiterating for effect)
Pleased with the battery life is to say the least.