explain?
I'm pretty sure I've talked about it on WF before, but it basically comes down to these few things.
1. Have you ever tried to contact Google for support? Now try to contact them when you have hundreds of dollars on the line. Good luck. Not gonna happen. At least PayPal has people you can call on the phone.
2. Want to have customers pay you from other countries? Not in the U.S. - too bad.
3. Like money? Too bad. Say a customer decides to file a chargeback at, oh, whenever the hell they want. Guess what? Google automatically issues the refund no matter what. Nothing you do will get your money back. Basically, if you use Google Checkout, enjoy giving away free shit and getting charged a fee for it.
And that's just for starters.