Petite female here.
I use it as a portfolio display on-the-go, networking instead of my huge 2nd gen iPad.
Movies on it are awesome in bed and especially at the gym. I used to bring my iPad to the gym.
I didn't love it until I took pics with it and OMG. Even my DSLR is getting dusty now. The details are amazing (for a phone cam).
I usually use bluetooth when on the phone, so holding it to my ear is a non-factor.
I feel less secure as a small female in NYC. The 5S was easy to grip well and hold securely. This protrudes from my tiny hands, making it an easier snatch. But pre-version 6, crooks were beating up people who resisted giving up their phones. So I'm not sure that the size matters as much as the value of iPhones.
It took 3 days to grow on me, but now I love it. I also usually carry a backpack or bag large enough to hold it. Plus, it's harder to sit down and lose