A standard shrimp tempura roll provides 550 calories.
From a strictly caloric standpoint, that's equal to 13 Chicken McNuggets!
Sushi can actually be very nutritious, thanks to its healthy proteins and fats (especially avocado), but tread carefully when it comes to rolls with tempura (a.k.a. "deep fried" -- a real shame to do to something as healthy as fish) and/or eel (which is cooked in a special sauce that contributes calories and added sugars).
Best bet? Start off with a high-fiber appetizer like edamame, steamed broccoli with garlic, or steamed spinach to make up for the white rice's lack of fiber. Then, choose any rolls that do not include tempura or mayonnaise.
Every sushi place I have ever gone to serves green tea for free, so have a cup or two along with the beverage of your preference for some bonus phytonutrients.
Above all, savor and enjoy!