Yeah, it's kind of lame.
I understand that I am a heavy user of my phone. But here's an example. Last week I ran a 5K. I unplugged from my car charger with the battery at 75ish percent.
I took a few photos, coordinated with my friends (text and talk), that was about a half hour's use. Then I ran the 5k - running CardioTrainer (with GPS) and Spotify. I'm slow but a 5k is still only half an hour.
At the end of the 5k, I had 28% battery.
Reading the internet, though, it seems I may have ended up with a lemon. There are a few people complaining of similar issues, almost all have had it go away with an exchange. I may try a factory reset and see what happens, not that I feel like loading everything again, but whatever.