Sorry if this is mostly a repeat of my review on Yelp, but my wife and I are so thrilled with this little restaurant that I felt obligated to post a review here as well.
We have gotten take-out four times from Ninja in the month-or-so since they opened, and we were very impressed on all occasions. A couple times, we ordered 2 of the 3-roll maki lunch specials so we could test out an assortment of rolls, and everything was very fresh and tasty - and the portions were a very good size. (Nothing gets a new sushi place's menu thrown out faster than when you can't find the fish inside the roll.) And the onion soup was spectacular.
Another time, we ordered dinner, and aside for some rolls, we also got the Spicy Kani Salad (delicious!) and the Manhattan Jalapeno (a sort of "sushi jalapeno popper" - also very good). They had a coupon for a free spicy tuna roll with any order over $20, and while they could have skimped on this free roll, it was just as tasty as everything else we ordered.
I can't tell you if the sushi here is on-par with the fanciest places in NYC, but I can tell you that it is just as good (if not better) than some of the smaller, reliable sushi places in our area: U-Yee, Fuji (the restaurant in Dayton, not the buffet), etc.
I don't write too many reviews on here, but I felt compelled to leave a good review for Ninja Sushi because I want to make sure they stay open. The location is very odd, and there has been a lot of turnover there over the years. The address is 1864 Arlington Ave, which is basically in the middle of a residential area between Cozzens and Jersey Ave.