After some brief online research back in mid-2007, I booked a twin and a double room online for 3 friends and myself. There weren't any reviews on HostelWorld, but the price seemed normal for Nairobi.
When the taxi pulled up at the place, even the driver raised his eyebrows, it was a ramshackle building with a smashed window in a slightly dodgy neighbourhood from which you could SEE the heart of Nairobi, but I wouldn't have felt comfortable even walking that short distance to it.
When we got inside, we realised that the phrase 'Youth Hostel' was a gross exaggeration - it was more like a halfway house, or seriously dodgy student accommodation. Which I think it was - the dorms we walked past were full of young locals, who appeared to be living there, not visiting.
The woman who came to deal with us was completely oblivious to our online booking, she said the person who owns the place and accepts the bookings is hardly ever around. Great.
The place was sort of open plan, and the area leading to the scary toilet wasn't undercover, and a TV loudly competed with with some of the residents' music.
To begin with, the rooms she showed us to had no locks and the 'double' was a set of ancient bunks. The state of them was shocking - an old calender in the wall had razorblades balancing on it, there were scorch marks around the power sockets, and lo and behold, the broken window we saw from the front was ours.
We were all kind of in shock, then after the woman left we tried to make light of it and laugh at how bad it was - but when it sunk in, we found the woman and asked where we could find internet access, and she gave us directions to a net cafe a few blocks away. On our walk, we veered around a woman who was lying in her own vomit.
After using the net to get some phone numbers and addresses of some cheap hotels in the city centre, we returned to Ngara, got our bags and left. We went to the first place on our list, which was in the city centre, and one of us jumped out to check if anything was available - thank God it was. The most amazing thing - this clean, simple, well-located hotel (Terminal Hotel) barely cost much more than Ngara did, but what a world of difference.
I've been backpacking for nearly two years solid now, and I can assure you this is the worst hostel I've seen on 4 continents. Beware.