Based on the recommendation of od and Dustin in another thread, I tried Koo for the first time last night. In a word, fantastic.
First off, everybody was very friendly. Ayumi-san, who took my reservation, greeted us, and handled our drink orders, was a delight. Her husband, Kiyashi-san (whom we requested thanks to od's recommendation), prepared our food. He was friendly, engaged (moreso as the night wore on) and eager to talk about ingredients and preparation. The other two gents behind the sushi bar were also delightful.
The food was terrific. As it was our first time, we left all decisions to the chef (except for when my husband asked for natto, a request he handled expertly by mixing it with other items into a very tasty hand roll). So we received a mixture of hot and cold items, prepared things and sushi and sashimi.
Of the sushi and sashimi, highlights were kampachi sashimi, razor clam sashimi, sanma nigiri, katsuo (in season right now) japanese barracuda nigiri, and blue shrimp (amaebi) nigiri, properly served with the fried shrimp heads.
I really appreciated both the freshness of the items I knew, but also especially the introduction of some things I haven't had before. I've cooked sanma but never had it raw; and the barracuda is something I'd never seen. This combination is what makes an omakase at a sushi bar really special.
Of the other items, we really enjoyed the 'spoonfuls of happiness' that began the meal. One spoon with tai (?) wrapped ankimo and the other with mendocino uni and quail egg (I'm leaving out a couple of other magic ingredients). It was a good way to welcome us and get things started. Refreshingbut lush. I also really loved a hot vegetable course that had miso eggplant, an amazing yellowtail-stuffed veggie, and some wonderful fried smelts with curry salt.
One thing I found interesting about the restaurant was that the sushi bar was making a lot of crazy rolls with sauces (things I usually avoid, and which we were not served). Often places that serve those things don't have the highest quality straight-on sushi, in my experience. But here they seemed to do everything.
I should also mention that the price was quite reasonable. The food charge was $75 each for a very satisfying meal with lots of interesting and high quality ingredients, as well as the full attention of a the chef. Although he was making many other things for the whole restaurant, we never felt ignored.
I feel the need to compare Koo to Ino, which has been my favorite for many years. I do think Koo compares favorably. Another poster mentioned that at Koo he often asks to skip the prepared items and sashimi, and just get a parade of nigiri. I might try this next time in order to be able to make a true comparison, as that is what one always gets at Ino. Based on what I know so far, I'd say that for the 'staples' like tunu, hamachi, I think Ino's is a touch better, but it's been a while and it may just be the rice making the difference (see below). But I get the feeling that at Koo there will always be highly seasonal variations beyond those staples that will not be found at Ino. Ino has some of that, but I feel that Koo is trying harder to do this, and it makes a difference. Koo's fresh grated wasabi is excellent; I don't recall whether Ino does this. One place where I have to say Ino wins, though, is the rice. His warm, flavorful rice affects the flavor of the whole bite, and there is a certain, whole-body satisfaction that it adds which is hard to define. Also, I believe Ino's soy sauce may be better; a bit thicker, with a deeper flavor. Last off, on price, Koo would have to be the winner. Better value.