And my card details are never provided to the merchant with Google Wallet.
Not to mention they are supposed to be connected but if you don't have reception or there is an interruption to cell service you can't pay.
With Google Wallet you need a connection to periodically (15 minutes, 24 hours, infinity) enter the PIN but other than that you don't need a connection to make a purchase. I have my PIN timeout set to 24 hours and I just make sure it's unlocked before I go somewhere where I might use it.
With a connection I get an alert when the transaction goes through (as soon as I get a connection if I don't have one at the time) and a later email verification of the payment.