IEM is a unique environment, no matter what office you work in. It takes a particular personality type to fit in at IEM, and if you don't have it, you probably won't be happy and probably won't last long. Unfortunately, it's a tough environment to explain or quantify.
My least favorite part of working at IEM is work-life balance. While there is some flexibility in working hours, whether you do project work or you are on the administrative side of things, getting the job done can sometimes mean long hours, with evenings and weekends involved. It can be really hard to have a personal life, and sometimes it is really hard to schedule time off or vacation (or actually take the time off you scheduled). Sometimes you have to be really aggressive and assertive to be able to take time off.
Another big problem is the lack of opportunity for professional development. The company doesn't provide any, and if you do it on your own, you do it on your own dime. That can be really frustrating because you can feel like you are stagnating, and the job can sometimes get monotonous.
One other challenge is the lack of opportunity for advancement. Basically, unless you move in to management (which is not an easy thing to do), there is no way to advance, and transfers to other departments or directorates to advance are extraordinarily rare. Rumor has it that a career ladder offering opportunities to advance is in the works, but that has been talked about at least since I started at the company. I'll believe it when I see it.
As far as salary goes...I'm not sure how we we compare. I've heard from people in certain disciplines, mostly in the software development area, that our salaries are low compared to similar companies. In my own position, salary seems to be on the low side of average based on the survey's I've seen. Raises can be tough to come by because they are based on the success of the company, not on any kind of set COLA or anything like that. In good years, you do well. In lean years, not so much.