I love the "Fire In The Mouth" roll with jalapenos (also tried the Marilyn Mon-roll which was good as well and comes with a rice wrapper instead of rice and seaweed if I recall so it's a "lower carb" option.)
+ They have a nice small sized house salad with wasabi in the dressing.
+ At lunch they gave me a free miso soup.
+ They sell Asahi Dark which is one of my favorite beers and you rarely see it.
+ Friendly staff.
+ Very conveniently located near a Sprouts health food grocery store so you can run other errands and they probably get some of their produce fresh from there.
+ The low carb sushi rice wrapper idea is inventive.
I live near Japantown in San Francisco and I can tell you that this place is very good.
I tried Bei (also near Scottsdale) a few months ago and didn't like it as much but I think they'll probably do ok because they seem to appeal to a younger crowd that just doesn't know any better.
When I travel outside of San Francisco/Japantown I miss eating Japanese food and I always try the local places but usually end up disappointed. I find that most Japanese places outside of major urban areas are not that great...for instance, I ate at 3 Japanese places outside of Baltimore, MD last month and none of them were very good.
In short, if you are visiting Scottsdale from a big city and you are missing good Japanese food you will like Sushi J. Dinnertime seems popular but lunchtime is more quiet and slower if you don't like crowds - the restaurant is a nice cool dark break from the heat outside.