I have had every iPhone since the 2G and have had the 5 since release day. I own pretty much every Apple product available and it all matches, so I'm a huge Apple fan (despite previously being an exclusively Linux/Unix developer but I digress)
Anyway, STAY AWAY FROM THE IPHONE 5.
I am on the phone alot, average of about 3-4 hours a day and the damn thing drops signal constantly. I have even switched network twice to try and get away from it but no, it's the phone.
Get a 4s or wait until the 5s comes out, the 5 has terrible performance as an actual call making phone.
As a smartphone, however, it's still absolutely excellent and aesthetically its beautiful and light. Just utter crap for making calls.