Based on our four previous meals at Fultons ,it has undoubtedly the most rude and indifferent service of all the restaurants at WDW. From the podium greeters, through the servers and right on down to the table cleaning staff--these folks could care less if you enjoyed your visit or not, or if you ever came back.
Now that said, the food is pretty good (tho $$$).
Flying Fish is a pretty good seafood spot--in fact, most of the hotel table service spots have several nice seafood entrees.
Offsite, the Celebration Town tavern has a nice selection of seafood.