We have never eaten there but I have heard the food is lovely and service great. It is rarely, if ever, crowded so, yes, I would say it is worth a TS credit just as much as any other resort TS restaurant.
ETA: The Yacht Club itself is a lovely resort - we have enjoyed a drink (or two) in the lounge there. It really is beautiful - and VERY different to AKL.
"Yes", it's worth it. Also, DS and DDIL ate there for lunch last month, and DS called it "the hidden gem of WDW resturaunts". He raved about how great it was, excellent service, beautiful (and peaceful) atmosphere, and the delicious cheesecake.
I think the food is very good there, atmosphere is lovely and colorful, service is good.. We usually do it for breakfast, but have had dinners there as well and have never been disappointed.