I recently heard a news that Google checkout now spreading thir legs across the world to beat paypal in the competition. But It is not gonna be easy to set up a mark as paypal has already the king at the moment/
Yes i have used both of them. What i like about 2checkout is integration with AdWords. This allows preferred pricing on some of the services. Google allows the users to automatically pay transaction fees with the earning from AdWord account. Moreover, when the ad is displayed on other web pages and in search engine results. a shopping cart icon appears so that it is easy to see that you can increase sales.
I have not used google checkout yet. I doubt if it is available in all the countries. Till now, i never faced any issues with paypal and i'm satisfied with that. But the only problem i have with paypal is it does not accept Debit cards in my country and loading funds into the account is a real hassle.