The best feature is that it has an integrated payment gateway so I can collect payments directly from my website through their API or by accepting Paypal as a third party provider for recurring billing. It's also great because they provide analytics of all your visitors' activity across different channels like email marketing campaigns etc., which helps me understand what works well and where there needs improvement. Not much; actually nothing at this time! They have good customer support though if you need help just reach out via live chat/phone call. We use countables primarily for our newsletter signups but we are looking into other ways we could be using them - such as sending emails when someone signs up for one of our webinars.