I have. It's very nice. It normally starts about 6:15-6:30. It's a buffet dinner. When we went they had grilled vegetables, pasta, chicken, beef and more. For the kids, they had chicken tenders, fries, macaroni and cheese, etc.
The tables are set up right next to a gate where Shamu is in a pool with the trainers. The trainers talk about training Shamu and so forth and then Shamu swims up to your table for pictures, etc.
It was a nice experience. I probably wouldn't do it again, but it's nice for one time.