Location!!
This is such a great little hotel. We stayed here for four nights as part of our honeymoon. After check in, which was quick and hassle free, we arrived to the room to find a card saying congratulations on our honeymoon, and a free bottle of champagne and chocolates.
Now, the rooms are small, but i knew that already from other reviews on Tripadvisor. The decor is just lovely, bright modern colours and modern furniture mixed with the old style of the building. We were on the 9th floor, and had a room that overlooked a roof of another building. This wasn't a problem however, as it made the room quiet, even at night with both the windows open we still couldn't hear any street noise. I found the beds to be a little uncomfortable, a bit to firm for my liking, plus i am used to sleeping in a King bed, this was a queen.There is a large flat screen television in the room. No coffee machine or bar fridge. However, in the lobby there is free help your self coffee and cookies, plus chilled water.
It wasn't particularly warm when we visited, but i noted that in terms of cooling they only have a ceiling fan and the windows which open. It wasnt an issue for us though during our stay.
The concierge was fantastic, outlining everything on our map that we should see and how to get there. We bought a three day muni pass for $21 which gets you access on all the cable car and other buses that run. San Francisco is a fairly easy city to navigate, the public transport is pretty good. There is a bit of wait for the cable cars however, and sometimes they get so full they just go straight past.
The location is great, right in the action. Its a shame there are so many homeless people, it started to become a real turn off that you couldn't walk anywhere without someone asking you for money. 
I would totally stay here again.