Wow, what a sanctuary. Who knew that you can be in the middle of Nairobi and feel like you're in the middle of the Knysna forest (back home in South Africa). No cars! No hooting horns!
The fact that non-residents are charged different rates (and that they want to sell you maps for KES500... so I just downloaded one on my phone) aside, I really enjoyed my walk though the forest. I did, however, see two small dumping grounds of rubbish (toner cartridges?!), which was not great. However, the walk down to the river was just what I needed to recharge. The forest appears popular for locals just coming for a walk / run as well.
Would have been great to have a bench here / there (especially at the waterfall), or a little kiosk selling snacks at the entrance perhaps. But if you plan poperly you won't get hungry :)