Pluspunten
Excellent salary and benefits package that far exceeds most private sector or government employers (btw it's not tax free as others have indicated here - you will pay around 30 per cent UN tax plus pension and insurance contributions). Incomparable opportunities to see parts of the world most people would only every see on television, and if you invest yourself, and bring the right skills, experience and attitude, you get to play a role in changing others' lives in some of the most challenging places you can imagine, and work alongside a real mix of intelligent and experienced professionals. You will have the enviable position of being able to advocate with governments for major social change, lead campaigns that put children's issues on national and global agendas, put assistance where it is needed in the worst of times, and build long-term solutions in calmer moments. The organisation is gaining a new momentum and increasingly being perceived as a new player in a changing world. But you have to work hard, and work long and sometimes antisocial hours, weekends, and occasionally during holidays (of which most staff receive at least 25 days per year). But that's the nature of international development work. It doesn't run to a nicely fixed schedule, and it's not the private sector or national government! That's why the work is so handsomely rewarded. If you want a 9-5 job, if you don't want to have to work very hard for your money, or if you don't want to have to move to a new place every few years with your family, this is probably not the organisation you want to work for. People say there is little work-life balance .. but if that's what you are looking for, you shouldn't be considering international development at this level. Also be aware that consultancies at UNICEF are not the same as staff posts, and that's why the level of experience demanded of consultants is usually much less than for staff positions. And yes as a consultant you will have to have your own health insurance, pay your taxes, and you won't get paid for days you don't work - as is the case with most freelance work. This is not unusual in any business model.
Minpunten
Like all large employers, UNICEF has faced its challenges especially in the human resource and administrative areas. New HR management will hopefully bring the agency into the 21st century and overcome what are known to be considerable headaches with recruitment time, unnecessary bureaucracy and slow processes. There is still some deadwood, mostly pre-retirement or classic civil service technocrats working out their time, but hopefully the organisation will get tougher and move people out of jobs they should not be holding. There is also a new school of mid-level managers emerging that is pushing for more efficiency and higher standards; but this is not the private sector. No sleep pods here.