I had a chance to spend some time in Nairobi in September (2010). The city is quite nice and the weather was cooler than I expected for a city that sits on the equator. I stayed at the 680 hotel downtown (which wasn't the best of hotels, nor would I recommend that others stay there). I went to the Nairobi National Park, the Giraffe Centre, and spent some time in the markets (I was only down there for a day). The Giraffe Centre was a nice experience, as I got to see giraffes up close an personal. I even got to fed one of them, which ate right out of my hand. The National Park has a number of animals (no elephants) and I was able to see lions, cheetahs, monkeys, and other animals as well.
I had an authentic Kenyan meal at Al Yusra resturant, right beside the Jami Mosque downtown, which was very good. I also had a chance to go shopping and pick up a few souvenirs.
Overall the trip was quiet nice, and was slightly better than I expected.