Mosser is a great spot in great location with great staff. They have great green fun products, breakfast etc. It is a no brainer if you want to watch your cost and be in the best location in the City. I stay here a lot...

The best thing about the Mosser is the price for the location. Rooms are small and bathrooms and toilets are shared.
The best way to describe it, is as a posh hostel. I did admire their commitment to being a 'green hotel' with enviromentally friendly shampoo and conditioner and a 100 % cotton robe (which is not thick enough to cover nakedness mind you).

I was caught in an earthquake tremor during my stay there. If an earthquake wasn't scary enough, the way the room shook was. I thought the building might collapse, a downside to staying in an old building.
The service at the front counter was okay. There is no restaurant on site, but one next door, which I found to be quiet pricey considering the lack of choices on the menu.

I would recommend to a friend who was on a budget.

Clean, fairly modern, helpful staff! Rooms are fairly small and facilities are shared but given the price I was more than fine with that compromise - maybe I'm not as fussy as some but I wish more cities had an option like The Mosser.

I also left my iPad in the room, thankfully cleaning staff had already found and secured it for me to collect the next day - very honest.

As a diabetic, I'd only ask that their breakfast muffins include a sugar-free option in the future. Not really a complaint, so certainly happy with my stay overall.

The Mosser hotel has everything to cover your basic needs but not much more, so if you expect 5-star experience its not a hotel for you. For those who need just a base for their stay and don't plan spending much time in hotel room - the Mosser is just what you've been looking for!
It has excellent location, good price, the rooms (though tiny), public areas, bathrooms (including shared facilities), etc are nice and clean, and beds are comfortable. The ceiling fan (rooms have no A/C) is sufficient to create nice breeze if the room feels too warm.
I must point out that even after reading the reviews and knowing to expect very small room I was none the less taken by surprize exactly how small the room really was. I mean there was only about half meter spare room on each side of the bed to move around (stayed in queen room with shared facilities). As I was traveling alone and did not plan to spend much time inside hotel it did not diminish my general satisfaction with my stay.
Will definitely stay again in Mosser when in SF.