You can't ask for a better location and we didn't need to use a taxi once. We arrived on the BART and took a short walk up Powell to the hotel, literally took less than 10 mins passing through Union Square etc. You can also grab the cable car literally from the reception door.
The hotel rooms are a good size, clean and with all the amenities you would need. We had a room facing Bush on the 5th floor and didn't have an issue with noise (as with any big city you expect to hear some noise!). The staff are friendly and helpful, they also have an Internet pc with printer in the lobby which we used for tickets etc.
Great base for a short stay in SF!