Not as great as these reviews say
First off the staff were great, and couldnt be faulted.
View of a concrete wall and alleyway was disapointing from 3rd floor room. Australian travellers beware of location, not as close to union square as you may think. Wouldnt dare leave the hotel after dark...
On first arrival, we instantly had a bad feeling. We had to drive through the so called tenderloin to get to the hotel. This neighbourhood is very rough. The best part of the hotel is the lobby Then it goes down from there. Although the hotel is very clean, the bathrooms and room in general are small and outdated. We had a dividing door to the next room therefore could hear kid screaming and smell cigarette smoke coming under the door. 
The toilet you have to sit on an angle because of its close proximity to the wall. The shower floods everytime you have a shower being a bath/shower and we found the bath only drained when it wanted too...
We felt very unsafe staying here for 4 nights i would reccomend to stay near pier39/ the wharf. The serrano can only work with what its got being an older building ( and the neighbourhood its in ). Updating rooms is a must. 
The connecting resturant was great. sitting at the window in the resturant will give you a good idea at what your in for on the outside. You get hit up for money and smokes when exiting most buildings and c stores by bums and crackheads.
For the money your paying for staying here, there are many better options around san francisco.