I wrote back into December 2007 that 70% of my customers prefer PayPal over GoogleCheckout, given the choice. I re-checked the figures today to see if GoogleCheckout was gaining traction with my customers. It isn’t.
% of UK customers choosing PayPal vs GoogleCheckout by month
I’m glad. Despite PayPal’s recent flakiness (since improved) and higher transaction fees, I still prefer them as a payment processor due to Google’s confidential email option (which a pain in the butt for support), lack of multi-currency support, chargeback fees and slow processing of many orders. It is useful to have an alternative to PayPal though.
 GoogleCheckout only lets me accept payment in pounds sterling, so I only offer it to UK customers.
 For a £19.95 transaction PayPal charges me £0.68 and GoogleCheckout charges me £0.45. But Google currently refunds transaction fees for 10x my adwords spend, meaning I don’t pay any transaction fees at all to Google in a typical month.