Firstly, sushi is meant to be eaten fresh, it is never meant to be premade and packed into a fridge. Rice for one thing is never meant to be eaten out of the fridge, it gets hard in the fridge and is not pleasant at all. Also, the items rolled into the sushi are often much better at room temperature, but that's just my opinion.
Secondly, the sushi they make in supermarkets always has a horrible rice to filling ratio (too much rice) and the flavor of the rice is always bland or overpowering.
Needless to say, I am not a fan of supermarket sushi at all. Please, find a supermarket to prove me wrong.