Very difficult to progress your career if you are on client site, unless you are able to travel on a regular basis.
AMS tend to manage staff on a reactive, day to day basis. In my experience there has been no evidence of proactive succession planning, supported with solid development plans.
They hire in the moment, often cherry picking staff. They do not always advertise the opportunities or give a transparent message to the local team.
The AMS mandatory internal promotion assessment process is not always followed - some staff skip this, getting an easier step up the AMS career ladder.
Staff development and growth is claimed to be a big focus, but in reality this goes to the bottom of the mangers priority. It results in this being a task, urgently needing to be ticked off, and a rush to get reviews completed each year. This rush often impacts the setting and the structure of the meeting. Doesn't make you feel particularly inspired or valued as an employee.
A very frustrating place to be, especially if you give the commitment and work very hard.