The Mucky Duck has acquired a reputation as a "must-do" on Captiva. So, we dutifully went there for lunch on our first day on the island. In retrospect, I can't say how it became so famous. It's right on the beach, but you really can't see the beach from the restaurant. It's ostensibly a "British Pub", but the decor looks more like a rural Midwestern supper club with pine paneling and lots of beer signs.
The food wasn't bad, but it wasn't fantastic either. The menu is divided between American-style food with some seafood specialties, and British items such as steak pies. We tried the fried oyster sandwich and the grouper sandwich. A large selection of beer (British and American) is available. Prices are reasonable.
We walked by the Mucky Duck at Happy Hour and noticed that they have live entertainment (a Jimmy Buffett soundalike) on the beachfront patio.
I would go back for a quick, inexpensive lunch, but I certainly wouldn't call this a "destination" restaurant.