2Checkout v1 was pretty decent for recurring billing, but v2 is a mess and is a real pain in the ass to work with. They make it impossible to run a business without a ton of trial and error on the billing side. Needless to say, that's a disaster waiting to happen. Worse - they're really expensive, and you don't have access to your customers' credit cards if you want to move to another billing provider. Skip these guys.