Pros
Work-life balance is okay (depends a lot on your manager though). Salary depending on the grade is good for a single person only, not for a family, especially if relocating internationally. Copenhagen has become very expensive in the past few years and salaries were not adjusted to inflation. Impact of your work.
Cons
Different contract modalities (Consultants vs Staff), Staff have better protection, and consultants can be fired at short notice for example. 3 days at the office, whilst most organizations (e.g. UNFPA, private sector etc) only require 2 days at the office, I guess mistrust would be the word here. The salary setting for international consultants is not very clear. Career progression does not have a clear path, it's understandable though, as it is an international organization.