Has anyone had experience with implementing and using Paypal and Google Payments to accept payments? Any opinion on which you like better and why? I notice some sites are supporting both now and letting the user choose...
If you haven't used any of them before, and do not have any constraints, try Paypal first. Once you are comfortable, you can start using Google. If you want to save the last penny, start with Google Checkout. They offer 0% transaction fees until the end of 2007. If you want to make sure your customers do not face any glitches, use Paypal. Google Checkout still has occasional problems (no major ones).
We implemented Google checkout last october. Before that about 5% of our business was through paypal, though a far larger number of our customer support cases were related to it. After introduction google checkout is about 30-40% of our business now, and paypal has nearly disappeared (this of course doesn't preclude people using paypal with google checkout instead of paypaling with us directly). If it wasn't for our ebay sub-business I doubt we'd be using it at all come July.