Am Kenyan - Born and raised and I lived at the Kenyan Coast. Kiswahili is very widely spoken and loved here. I studied Kiswahili as a language and i very much admire the rich vocabulary and idioms. It is both a national and an official language in Kenya and most of Eastern Africa.

Majority of Kenyans and East-africans are multi-lingual and they will speak on average 3 languages (English, Kiswahili, the mother-tongue and most likely an additional local language.) if they are Bantu, they will also understand 3 or more other languages and same if they are Nilotic or Cushitic.

If your are foreigner, visiting for tourism - you will very much unlikely understand Kenyans! and if you are a foreigner of they type " i lived in Kenya for 10 years" most likely in a posh residence in Nairobi or Mombasa -- Kenyans are likely to have spoken to you in English throughout! Do not mistake that for the idea that Kenyans only speak in English - remember i said majority are multilingual and given that we have over 42 different languages - the language that mostly unites us is Swahili - it is also deemed less elitist.

The language is spoken across the entire East africa - (Tanzania, Kenya, Uganda, Mozambique (Swahili name - Msumbiji), Burundi, Rwanda and Eastern DRC Congo.)

The article is an excerpt from a more detailed book and I agree with most it - but the author could have done a better job at investigating the origin of the language and early spread. It has borrowed heavily from Bantu, Arabic (countless words) and Portuguese (e.g. Pesa - money in Swahili, Meza - a table in Swahili).