I have used PF since 2010 in a Solo Family Practice office. 10 employees.
PROS: Easy to learn for ALL levels of employees. Tech Support is good. Templates are easy to customize. Flows closely to a paper chart. Works well for MU and other Data driven needs. Billing & schedule are simple. It's FREE!
CONS: Changes/improvements recommended by users almost NEVER get done. Such as a request for "patient alerts" that pop up when a chart is open, were promised to be developed in 2010 and still don't exist. All focus of PF went to MU. Highlighting chart text, inserting video, or scanning directly into a chart note by attachment STILL can't be done to my knowledge. You can't assign a patient to a certain Practitioner and adjusting a med or using generic shows up as an additional med in the list.
I billed through their associate, KAREO, and things went smoothly. QUEST labs interfaced well.
PF is not perfect, but remember it is free. Be prepared to create "work around" processes for your staff to deal with certain glitches or annoyances... like the lack of alerts, etc... otherwise, you will be pleased with the ease of use and visual simplicity of the software.