If you only have a half day to visit I highly recommend this tour. The elephant orphanage is tremendous,we actually adopted a baby elephant. The giraffe center is a quick stop to admire these amazing animals and feed them,and finally if you are a fan of the movie Out of Africa as I am you will really get a kick out of visiting the home of Karen Blixen. The driver picked us up at the hotel where we stored our luggage and then off to the airport to fly to Arusha.
Possibly over-priced as there are very enthusiastic, and cheaper, taxi drivers willing to drive you to and from destinations. But my guide was happy to deviate from the route to show me places of interest and was well-defined in history, issues and possible future of Nairobi