Triallists will be able to pay for goods worth under £10 using their phones at selected stores where readers are installed. Obviously being able to pay for goods in this way would be very fast, but in order for it to completely replace your wallet, all high-street shops would need to install readers, which is a long way off.
Another issue is security and how safe the system is, relative to using chip and pin. But Barclaycard and Visa assured us this is something they take very seriously, and adequate security measures would be installed for large transactions.
But what if your phone is stolen? All of the partners said that in any public version you would be able to call a number and get all three services disabled. Obviously you'd need to find a phone first, which could prove tricky depending on where you were robbed.