I stayed at the Jupiter Guest Resort for four nights throughout the month of June. Compared to the rest of what is available in Nairobi, JGR is likely the best value by far and I highly recommend it (with some caveats).
Nairobi is an expensive place to visit. Most 'inexpensive' hotels are well over $100USD per night and are on par with budget hotels in North America (that would normally cost less than $100USD). I also stayed at Hotel Boulevard and Hotel Kivi Milimani, and these experiences are what form my comparative opinion.
While the other hotels I stayed in were certainly 'nicer' and more spacious, the significant disparity in price does not reflect the difference in quality. When I travel, I am basically looking for a clean, safe, friendly place to sleep with free breakfast and wifi, and that is close to places I want to see and visit. JGR fit the bill nicely, and then some!
The least expensive room (for 3,500ksh) is very tiny, but perfectly suitable for a single traveller looking only to sleep and relax a bit. The next room up offers a little more space to spread out and is only 4,000ksh. Wifi was free and consistent during my stay (had to pay for wifi at the other more expensive places I stayed), but check with JGR if this is important to you, as things can always change.
Although JGR is very close to a slum, I always felt safe in the area and especially in the hotel (of course, basic and universal safe-travel rules apply). It is in Langata and many attractions are in walking distance (within 4km). Carnivore, the national park (and walking safari), the Bomas of Kenya, etc. are all walkable. There is a grocery store across the road as well as ATMs. There is usually a decent arts/crafts market in the grocery store parking lot on weekends.
The showers are hit or miss. Hot water is not extremely important to me, or a good shower in general for that matter, as these tend to be a luxury with my kind of travel (i.e. I grab showers when I can, and if it's cold, so be it). The showers are the electric variety and seem to have only two settings: cold and scalding (the medium setting didn't work in the three different rooms I stayed). Just keep an eye on it and learn to not be so fussy...
The breakfast is excellent. Certainly less of a spread than the more expensive places, but more than satisfying for the average traveller. The cook will whip up some eggs for you on request (makes a great spanish omelette with chiles!) and there is always sausage or bacon, toast, tea/coffee, fruit, potatoes/beans, etc.
This hotel rates five stars for me because it meets and exceeds all of my expectations for a more-than-fair price. However, since my expectations are likely lower than the average tourist, I gave it a 4-rating to account for the small things that I can imagine might be a problem for others (showers, extremely small single room, etc.).
And also worth noting is the extreme friendliness I encountered from all members of staff, from the manager to the clerks, the security and the cook staff. All were ready, willing and able whenever I needed help with directions or transportation.
I can say without question that whenever I visit Nairobi again, I will stay at the Jupiter Guest Resort in Langata, and recommend it to others (with the aforementioned caveats).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.