I enjoy the sushi from Whole Foods - the sushi from my local Giant is probably a C+. The seaweed salad I get from Giant is actually pretty good.

The best sushi I've ever eaten was served at room temperature, or slightly cooler than room temperature. All of the sushi I get from supermarkets is refrigerated, and kills the rice. Fresh fish is certainly important, but cold rice (when it's supposed to be fresh, usually slightly warmer than room temperature) makes the roll tough.

Just my $0.02.