Depends on how your cutting. If your going low-carb, then the white rice is definitely going to sidetrack you a bit.
Sushi is my favorite food in the world and I'm sure it's great for you if your doing a low cal/fat diet. It's a staple in the Japanese diet and they live about 10 years longer than Americans on average.
If, like me, your cutting with a no carb diet though, Sushi is going to knock you out of ketosis unless you have it sashimi style which means no rice.
BTW, I suggest trying a hamachi roll if the rice doesnt effect your diet. Make sure the chef dices the yellow tail up with green onions. It's the best!