The API (http://support.recurly.com/faqs/api/accounts) looks very similar to the Authorize.net API, so I'm not sure that this service simplifies the integration all that much. Also, it isn't clear to me whether the accounts are stored in Recurly, or whether they are stored within the payment gateway.
Overall, I can't say that I agree with the premise -- I haven't found online subscription billing to be very painful. However, if I can be convinced that this service adds value without creating third-party risk, I'd be interested.