I stayed at Jupiter Guest Resort Nairobi Kenya for five nights recently.
Having checked all the other budget hotels in Nairobi (and finding most were charging far more than I'd been led to expect) I was directed to the Jupiter Guest House by my friends at Parklands Sports Club.
The location is very convenient for both the city centre and Westlands.
The staff were excellent; friendly and helpful. The en-suite room was clean and the bed sheets were changed every day.
I didn't eat there, so can't comment on the restaurant, but in every other respect I can highly recommend the Jupiter to travellers looking for low cost, safe, clean accommodation near the city centre and Westlands shops.