Pros
Good opportunities for visibility, especially good for making connections with EU institutions, foundations and Brussels-based NGOs. Quite flexible; mostly good opportunities for pursuing your own research interests.
Cons
Everyone is put on a scam 'self-employed' contract that means you need to register as a business handle your own taxes. No support or guidance is provided for this. This usually isn't made clear during the application process so it comes as a shock to discover 30-50% of your (very meagre) salary has to go to taxes, even if you're on the base intern pay (which is significantly below Belgian minimum wage). Negotiating any more than a 100-200 euro pay rise per year is effectively impossible. Limited prospects for promotion after you've reached Policy Analyst level (1 year-18 months at most). Working hours are flexible but in practice you are expected to deliver so much that you will be doing 50+ hours a week at a minimum. Overall feels exploitative and is rarely rewarding. Only for those who very much want to increase their profile as an analyst or win 'name recognition': for career analysts only.