Havent been to Nairobi but Mombassa is squalid ,poor,polluted and very,very dangerous after dark.
Was in country during the elections a while back and there were a great many political murders and maimings ,though not on the scale of the west of the continent more recently,most of which did not appear in the first world press.
Government corruption is rife,the World Bank contributed a very large amount of money to rebuild the coastal highway to Mombassa which is the main port for E.Africa not just Kenya and the money just vanished without so much as a pot of tar being laid.
The W.B. then had to give the same amount again to a Japanese firm to get the job done.
The police are often at least as dangerous as the criminals and poaching in the wildlife parks is carried out on a considerable scale by the park wardens themselves.
That said there are a lot of decent ,hard working and incredibly friendly people there and the country is still streets ahead of most other sub Saharan countries.