Wood building, looks a bit crude, especially considering it's next to a post office (Clinton famously greeted the customers in line on his way to the restaurant).
Reserve up to a month in advance; for restaurant reservations, you must make a $25 credit card deposit. For the upstairs cafe, you have the option of a la carte, whereas the downstairs menu is set each night (see this site for featured menus). You could try waiting it out at the cafe if you don't have a reservation.
My roommate splurged and took me out for a special occasion. In surprising luck, we got a table in the cafe on the same day, due to a cancellation. I was slightly puzzled as to what "California cusine" entailed - fresh, local, organic stuff? I ordered a white fish with a strange vegetable. Everything was beautifully arranged and tasted fresh, full of new flavors. We felt out of our element, as students, but the staff treated us courteously. A worthwhile experience, nevertheless.