Hi!
Have not personally done the Dine w/Shamu thing but have heard mixed reviews about it. Some people I have talked to enjoyed it and others didn't. The ones that enjoyed it the most are the ones that had kids with them.
I have done the Luau that they have there twice. And that is fun too.
We did it last year and loved it. The food is great and you really get up close to Shamu. The only thing separating you is a gate. It's outdoors, so it can be warm, but we loved it!