Beware this new convenient form of banking: ostensibly there to make your life easier, it is actually a way to completely remove cash/currency from circulation, and give ALL power and control over your lives to the Banksters.
If you don't believe me, just think about it for a minute: what if your bank decides that they don't like something you're about to buy; something you've signed up to on the web; someone you've corresponded with; some idea you've had which you're cirulating. In today's inter-connected world, it is easier than 1,2,3 to stop your line of credit, to block a card, or in this case, to send you a brief 'tranaction not approved' message to your mobile 'phone.
You will no longer be able to dip into your wallet or purse for that twenty quid to pay for some petrol, when you're in the middle of no-where, it's getting dark and you're miles from home....
It reminds me of that scene by those two blokes 'Computer says No', but it's much, much more sinister. It also reminds me of Huxley's 'Brave New World', as well as Orwell's '1984'. Welcome to the future, indeed.