Greton is located in a seedy part of Nairobi - ie River Road area - on the edge of the CBD. Its a good budget hotel for the price though grotty compared to similiar priced much nicer hotels in Mtwapa, Mombasa. Generally the staff are friendly, OK restaurant nextdoor, rooms + bed are adequate, hot water is great but the showers really look grubby.
The webite description and photos are a gross mis-represention of reality !!!! The flowers in the single room photo are completely laughable !!! I have been using Greton for over 10 years when passing throu Nairobi. Staying at Greton is definately 'slumming it' for sure but good for the budget.
The security is good to stop intruders from outside but not so good for the thieves inside. The inside windows of some rooms can not be locked and rooms easily accessed if not for lone security guard in the five floor hotel. Based on personal recent (Feb 2014) experience the management show no interest to reported (to police) thiefts and the two very strongly suspected persons are still working there.
Stay there if you are on a budget but get a room with a lockable inside window, leave no valuables for the staff to steal.