I have no problem getting through a whole day reading probably 10 emails (when I'm away from the computer), sending 3-4, sending/receiving ~20 texts, ~20-30 mins on the phone and checking a social media app a couple times.
The GPS and especially 4G really eat the battery. When I got the EVO, it would be at full charge when I went to bed and 20% when I woke up ~7 hrs later. Once I turned off 4G and GPS it would be at 80-90% instead of 20%. With this phone, I'm not in a 4G area and haven't turned on the GPS, I wake up with it at 90%.
Other than 4G and GPS, people have to consider the other factors that may drain more battery than normal:
-One of the largest, brightest screens and most power you'll typically find in a phone. If you're constantly on it running intense apps, it's going to use that power potential beyond what most phones can do pulling more power for the processing and to run the large, bright screen.
-It's a new phone, so you're likely on it more. Playing with new features, customizing it and setting it up. Once the newness dies down, it will level out more.
-It isn't a huge battery. If you're a power user with such a powerful phone and large screen and refuse to get off GPS and 4G, you're being unreasonable to expect all day use unless you get the large hump back battery.
I have no doubt 4G will become more efficient and battery friendly. With processors however, it's a race of two goals, power, and life... power will be winning that race for a long time with battery life trying to keep up just as it has with laptops. When I owned my laptop company that sold laptops with 20" LCDs, Raid and SLI graphics, it took everything we had to come up with battery management system that even had the power to boot up while on battery. It amazed me people who tried to game on battery with everything enabled expected more than 1.5 hrs of battery and would complain.