I'm yet to try the Crab Shack but I have heard very good things about it from people in the office. I believe it's also owned by members of the same family who run The Beach House on the seafront by The Dome which, by the way, do the best burgers I have ever tasted. Not an exaggeration. They...
Coast just along the beach just past Steyne Gardens is also very good, especially if you want a good sausage. All local produce and they have just expanded the building too (but not the kitchen, which is obviously impact the timings of service)