Big fan
I'll start by saying that I was sceptical of this hotel at first. I lived in the City for many years, and while I was a fan of Japantown, I thought that if I were visiting San Francisco, I would want to be located a little closer to the action. I couldn't have been more wrong. I am now a *huge* fan of this hotel, and I will probably return here again, at least a few times. 
First, the location is perfect. If you're a fan of sushi, or Japanese food in general, this is the place to be. Second, you're a block away from the 38 Geary bus, which can transport you anywhere of importance in the City, or at least to transfer stops. Third, for the more timid travelers, Japantown is relatively safe and quiet, and it makes for good exploring.
Finally, the rooms are quite large relative to other hotels in the City. Stay in a Union Square hotel, and the rooms are miniscule, for the same price. Also, spend a touch more for one of the Kabuki's rooms with a wraparound balcony. The views are exceptional, and it's nice to open the corner sliding glass doors on a nice day.
In general, this is a great hotel, with great service, and it now sits at the top of my list for San Francisco. Stay here.