We stayed at the HI Downtown in Early Aug 2014. The location of the hostel is great, just around the corner from Union square and Powell st, which are the central locations. On the other hand, the hostel is surrounded by homeless people which can be a bit intimidating, and a walk away from the town centre takes you to an area filled with homeless and alcoholics!
We had a private room for 3 people, with a shared bathroom. The toilet and shower are separate, and not a multiple block of showers like we imagined, thank god!
The room was clean and tidy but small, and the toilet and shower were also clean.
The staff were fine and friendly, although a list of rules did get reeled off when we signed in and we had to sign a piece of paper to agree to them. This included no food or drink in the rooms. This seemed a bit daft seeing as we had a private room. I could understand it in the dorms, but not so much in the private room. It meant we couldn't pick up a sandwich on the way home as we couldn't eat it in our own private space. Also, there is a vending machine in the hostel, but if we used it, we had to hang around at the machine drinking our drinks. There was also a noise rule, which is seems some people didn't care about as people kept us awake in the early hours on the morning.
Overall, you cannot fault the value for money and the location, and we were happy with these...it would've cost us 2 or 3 times as much to stay in a hotel nearby, and mostly we did not spend a lot of time in the room as there was so much to see and do in San Francisco. It would've been nice in the hostel had a bar though to relax after a busy day sightseeing.
There are great diners nearby just outside the entrance!!