> There is no user purchase validation step! I just swipe my phone and transaction is done. I get this is the same as using a CC but in theory there is such a huge opportunity to improve the experience. How about popping up a thing where I confirm the purchase, even add a tip or sign for some purchases? WTF???

I disagree with you here. I want the payment to be as fast and painless as possible. A "tip" screen, a "sign" screen, etc. would all be very annoying. I suppose adding these optionally somehow could work though.

On a technical note, it's not quite the same as swiping a CC. There's some authentication to start - you must authenticate on your phone (via fingerprint or pattern or whatever lock mechanism you have) before you can make a payment. In addition, a one-time token is sent instead of your actual CC number, so the retailer couldn't reuse your payment info. In other words, it's much more secure than "signing" ever was and you get some nice security benefits by using your phone as opposed to swiping a credit card.