I'd stay here again.

Liked: Everything I needed and nothing I didn't. Very friendly staff. No curfew. Allowed to bring outside alcohol back to the room. Complimentary breakfast of bagels, oatmeal, coffee, fruit. And they hung on to my bags for the entire day while i walked around the city before my flight. Comfortable bed, big bathrooms. Great experience overall.
Disliked: Nothing! It was great!

Superb

Liked: The place is nice, solid network, I have been to HI Hostel in New York, they have really nice beds, very good services. The locations is great, everything within walking distance. Definitely recommend especially if you don't have a lot of time to visit the highlights of San Francisco.
Disliked: -

Exceptional

Very good

Liked: The staff is really kind and helpful, fresh fruit is provided at the breakfast, the position is a good starting point to move around the all city
Disliked: The matress was not really confortable. It's a pity that the breakfast has only the sweet option and not the savory as well.

Nice

Liked: Only stayed one quick night and had a good bed/sleep

Very good

Excellent location

Liked: The location was excellent, near Union Square and the Powell Street Station which has BART and the MUNI Metro. Also the start/turnaround for the cable car is in the same location. There is a transportation kiosk near the entrance to the station for information. The hostel staff were very friendly and helpful. I checked out in the morning to go to a seminar, but my flight wasn't leaving until the evening and they held my luggage for me for the whole day, which I really appreciated. The rooms were clean and the noise for being in the downtown location was a minimum. The kitchen and dining area had everything I needed and was clean and well attended to. They even supplied a morning breakfast of bagels, oatmeal, fruit and juice as well as 24/7 coffee. They offer group activities such as tours, meet and greets and bar crawls if you are interested in mingling and getting to know your fellow travelers. This was the first time I stayed in a hostel and I would definitely stay here again when visiting San Francisco.
Disliked: The hostel is right in between the downtown/Union Square and the Tenderloin neighborhood. Be aware the the Tenderloin area just to the west may have safety concerns and there are a high number of homeless residents. Please take this in consideration when going out at night. The area where the hostel is located is safe, right on the edge of the downtown high end shopping district.

A great location for the...

Good

Liked: Excellent facilities, decent kitchen with good free breakfast. Conveniently located with friendly, helpful staff.