I worked in PA for 2 years from 2005-2007. Started as a constituency manager ($2700) and got a promotion to deputy constituency director after 13 months. Work was really tough especially if your MP is new and young. A lot of events to support and had to work on most of my weekends and evenings. Not a good job for someone who wants to start a family or settling down.
However, this job can open up many opportunities as you meet all sorts of people. Heck, even DPM came to my wedding