While it's technically correct that V.me is an online portal for payments akin to paypal, they're run by visa and for all intents and purposes, has your details already 
I've never really used it for payments, rather i use it for the security. There are different security features you can set for any of the (visa only?) cards you register, e.g. v.me will email me for each transaction i make overseas & online, as well as any australian transactions over $20, this applies also to transactions made outside of V.me
It was quite handy when I was overseas as I got instant emails for all my transactions, which also quickly alerts you to any fraudulent activity.
