Google (GOOG) really wants you to ditch the fraying leather billfold in your back pocket. The king of search just opened up its mobile payment system, Google Wallet, which had been limited to Citibank cards, to all credit and debit cards, including Visa, MasterCard, American Express, and Discover. 

That means you can now sync any credit card account with Google's mobile app, store the info in Google's cloud, and buy goods at the store simply by tapping your Android phone on a payment terminal. More than a big step forward for near-field technology (NFC) payment systems, the new Google Wallet boasts added security features, namely the ability to disable its services from a remote computer in case you lose your phone. 

Customers have been slow to adopt Google Wallet -- but are these improvements enough to take the app mainstream?

Maybe. Google Wallet is quite useful now. This is a "huge announcement," says Patrick Roanhouse at Betabeat. Whenever you tap your NFC-enabled Android at one of the 200,000 MasterCard PayPass-supported retail locations across the U.S., Google will instantly charge your chosen credit card and "give you detailed purchase information" right on your phone screen, allowing you to keep track of your purchases in one handy place. Before, Google Wallet was a novelty. Now it's legitimately helpful.

How useful can it be when it only works on a few phones? Sure, now you'll be able to use Google Wallet to pay with any credit card at places like Whole Foods, McDonald's, and Walgreens -- but there's a massive catch, says Claire Cain Miller at The New York Times: Google Wallet still only works on "six Spring or Virgin Mobile phones." Of course, you can also use Google Wallet on Google's Nexus 7 tablet, which is equipped to handle NFC payments, "but pulling out a tablet at a cash register seems more difficult than just using a credit card." 

Google Wallet won't go mainstream anytime soon. Google Wallet just got a lot better, says Casey Johnston at Ars Technica. But it still has a number of obstacles to overcome. Perhaps chief among them: Though 200,000 or so retailers have equipped themselves to handle NFC payments, overall, "brick-and-mortar store adoption of Google's NFC payment process is still low." Let's be realistic: "It will still be a while until users are hitting their phones against cash registers with abandon."

More from The Week

• Hotmail reboot: Will new Outlook convert Gmail users?
  
• Should Apple buy a stake in Twitter?
  
• 5 reasons Mac users should upgrade to Mountain Lion