Pros
I was a paramedic for AMR-San Diego for a quite a few years. The local management was always responsive to our needs while working. They took time to get to know there employees on an individual basis. If an incident occurs that could lead to corrective action, they will talk to you to understand exactly what happened. If you demonstrate that you learned from said incident, they are likely to go out of their way to minimize the any punishment you receive. That is my experience anyway.
Cons
Their mission statement includes something like "Patient Focused" but in reality, they are more concerned with with winning and maintaining contracts. EMT's and Paramedics are more likely to be punished for something that puts AMR's contracts in jeopardy than putting a patient's life in jeopardy.