Schedule a genius bar appointment and tell them that you just noticed some issues with your phone. They will look it over and as long as it isn't blatant damage (they will ask you a few things, like did you sit with it in your back pocket), use a special key to unlock a special drawer and pull out a replacement iPhone (probably refurbished, although mine looked brand new), pull out the sim chip from your own phone and put it into the new phone to activate it.

I didn't have to argue or answer a bunch of questions. Took about 10-15 minutes once my turn came up at the genius bar. As painless as it gets in my opinion. Try doing that at a AT&T or Verizon store, I dare you to get a better result.