Yes, we eat seafood at several WDW restaurants, and always find it very good. Cali Grill, Narcoossee's, Flying Fish, blueZoo, Hollywood Brown Derby, Artist Point - we've gotten good seafood at all of these. Oh, and V&A's, of course.
The sushi at CG is very good, we always order it when we are there - and we have a very good sushi restaurant near us. My DD dreams of Yoshi's tuna three ways, lol.