I had to use it 2-weeks ago, I washed my phone in the washing machine accidentally. Don't ask.
Anyway, I made an appointment and took it to the store they verified that my 4S had the AppleCare+ and they brought out a phone in the black container within 5 min. BTW, I'm not sure if they are refurb or new, but the phone looks as good as any that come out of the box. After he swapped SIM cards I paid him $50 and then I was set to go.
Pretty painless, but I feel that if they didn't offer + they would have probably replaced it for free, which has happened in the past with older iPhones. Oh well at least I paid for the coverage, had I not the replacement phone would have been $249+tax.