This month I stayed at the Serena for a couple of nights before and after a 3 week Safari trip. It was a great place to rest after a grueling flight getting to Kenya and a great place to recoup and recorganized after the Safari getting ready for the return to the US. Rooms are plenty large enough, well appointed, and comfortable. The staff is great and very interested in your comfort. Don't expect fast service from the restaurant staff they are expecting you to relax and assume you are not in a hurry.
Most importantly you feel completely safe and isolated from the surrounding city and unfamiliar environment of the big city third world city of Nairobi.