I haven't been to Sushi Zo for a while but went last night.
I loved Zo, going weekly (if not more), when it first opened but I must admit I got a bit burnt out, as it didn't change much. The quality was always great but the omakase was always the same omakase.
Last night just blew me away. I really don't think anything else in the city compares for straight nigiri sushi: fight-back-fresh fish, hand-made soy (and other) sauce(s), yummy vinegered rice and wonderful uni, ikura, abalone, oysters etc. I brought a friend who taught English in Tokyo for a while and he was spectacularly impressed.
I was especially thrilled by the difference in the menu, many new fish I hadn't had previously and rotation off of some I was tired of (no more butterfish).
It was superb. Urasawa, where I have been lucky enough to dine twice this year, is far more like Keiseki dining with a large sushi course than a sushi bar -- and it is 3x the price of Zo -- so I will leave it out of comparisons. Almost all the other sushi meals I have had in a while were nowhere as great as Zo.