Pros
Really almost none. Low money, dead directions.
Cons
The IMF and DFD are especially terrible places of work, even comparing to the neighbor institutions. Dead directions of research. After working on the topics you will be unemployed. Work in this type of organization is like a "human branding" for your CV. None of the German nationals would like to work here (as well as in any other Behoerde). Therefore they take foreign people who do not know the law and their rights. Look around - no German in the age of 25-40 works there, only the bosses and thoses who found nothing better. If your contract is not extended - go to an attorney. If you see any degradation of your status - attorney. Do not contact their Betriebsrat - they are together with the employer. A recommendation: find a normal regular job in a commercial company in a prospective branch even for less money. You will earn money after, but not loose the years of you only one life.