I came to Sushi Ko using a Groupon with one of my buddies. My buddy has been to Sushi Ko several times with his father growing up, so I was eager to try it out. Sushi Ko has the feel of an authentic hole in the wall sushi restaurant. I haven't found a non-commercial sushi joint in AZ yet. I was quite surprised because Sushi Ko is in mid/North Scottsdale territory.
We ordered mostly sashimis and non-cooked rolls. The fish tasted relatively crisp and fresh (considering there is no ocean in AZ).
Overall, I would definitely recommend Sushi Ko to authentic sushi fanatics.