No I haven't used it, because I need a new sim card to do so. I'll go to the at&t store tomorrow and get one, but the only store I know that takes it is CVS, and maybe best buy. Has that changed?
There are quite a number of stores that can take NFC payments, but then you do run into places that don't have it. Point is, both iOS and Android are/will be using NFC, so phones from either camp (that have NFC) will work at the same locations.
Another thing I realized about the watch, they have so many different methods of input, from the crown dial, to the comm button, to taps, presses, force touch or whatever that is, that's going to be really confusing for people. The input methods on their watch are actually more complicated than the phone and tablet!