It's very easy to use. I'm a wallet minimalist, so I hate carrying multiple cards. With NFC payment systems I can just tap the phone and pick the card I want to charge. It is also more secure in the US where pin and chip are not yet a standard. My phone is always at hand, my wallet not so much. If only we could get a digital drivers license I wouldn't even need a wallet any longer.
The biometric options are even nicer as I don't have to type in a pin. Just touch and press thumb.