It's been more than two years now since I got introduced to PayPal's Payflow Gateway. I have integrated this payment gateway in four to five of my organization's projects now and I must say it's truly awesome. Being built by a maestro in the payments domain - PayPal, there is too little or almost nothing to worry about. It allows you to focus on and meet your business needs and leave the rest to it. Right from day one of development, deployment and even post deployment, Payflow Gateway has stood out exceptionally well for us.