I have this service primarily for the ability to store a patient's credit card and automatically charge them when they have a balance due. Our accounts receivable has dropped precipitously. yay!
Appointment reminders are good to. We have it activated, but don't actually schedule on it since due to a couple of features/lack of features. But it does basically work well and gives a close to real-time update to AC (its bi-directional too).
For patient demographics, I read what the patient wrote, and type it into AC myself because the patients tend to misunderstand things and it can mess you up. it is still useful for getting the updated information though.
