Conferences and iPhone batteries have traditionally not been the best of friends for me. I have owned the iPhone 3GS, 4S and now the 5s. While at conferences, I am usually checking/posting to Twitter, (i)messaging, emailing, looking things up, and using Maps/OpenTable/Yelp to find the best dinner place. The 3GS and the 4S would barely make it mid- to late-afternoon before they were dead.
The solution was usually to hunt for power t hroughout the day, sneak back to the hotel room to charge up (and catch up with the office) during an afternoon session, or pack an extra battery case.
I picked up the iPhone 5s when it was released back in September and have used it during three different conferences. It has gotten me through the entire day. This despite the three conferences in cities, New York, Las Vegas, and San Francisco, that might have some of the worse cell coverage in the United States.
Running from the 7:00 AM breakfasts to the 1:00 AM last call, often I would be plugging it in with only a few percent of battery left, but I never got that sweat of imminent phone death. The whole time at all three conferences I remained on cellular data because wifi is always so bad at conferences.
Certainly, the camera is great, the speed of LTE is wonderful, and the weight is nothing, but to me, my nearly four months with the iPhone 5s is its ability to get through a full conference day (and night). This is technology getting out of your way to just do what you need to do.