Pros - it is front of UNON, relatively clean, ok if only staying for a few days and you don't care about the quality of where you stay.
Cons - Management is unprofessional, no flexibility, rooms without frills, internet connection only works sometimes, hotel rooms are a rip off and noisy. Apartments are very hard to book (months in advance) and are no frills plus you have to pay your own gas bottle for cooker regardless of how much you use it, fridge is tiny, not comfortable for more than a few days...but you need to book by the month, a bit of a trap. Duringmy stay there, I noticed there were a few UN consultants long-term in those appartments, they must have done the Sudans and the Afghanistans to be ok with staying in these appartments for long.
Honestly, there is a large number of guesthouses in the Gigiri area which are walking distance to UNON. If you are posh and don't want to be seen walking into UNON gate (ridiculous but hey, UN hosts all walks of life) book yourself in a luxury hotel and take a cab to work.
My best recommendation in the area is Gigiri Guest Cottage (google it to get contact details). It is a place with quite a history (ask the house staff). Service is top notch, the place is decorated with much taste and although a bit pricy for some, it is worth every dollar. They have 2 big dogs but are friendly.