On our most recent trip we stayed at the Poly, so we felt trying the Luau was a "must" to go along with the ambiance...
The food was decent, but it wasn't the best meal we've experienced. The salad and bread were yummy, and that was followed by ribs, baked chicken, rice, and veggies. The dessert is hard to describe...some sort of cake/pudding volcanoes. We enjoyed the "presentation" of dessert but it didn't taste that great.
Now the show is divided up into three acts and it starts while you are eating. The basic premise is there's a young girl who returns home from the "big city" and her wise aunt encourages her to remember her heritage. The first two acts aren't too exciting, but the third act includes the best performances, including a talented fire twirler.
Would we go to the Luau again? Probably not. Are we glad we tried it? Yes...like I mentioned before...it just seemed "right" since we were staying at the Poly.
Hope this helps...