DH & I have been twice, and the 2 experiences were like night and day.
1st time was in '97, celebrating my parents anniversary with 6 of us - parents, dh & me, and DS13 & DD16. We sat at the later showing and it was dark (which IMO adds to the mystique). We liked the food very much that time. We loved the whole experience.
So much so that we tried to repeat the fun on our '00 trip for our 25th anniversary (just DH & I), in fact that WAS our anniversary dinner. It was awful. Because it was early (first mistake), there were mostly family groups with many children. Mind you, I'm not bashing children, it was just not like the first time because the later seating was at 9:00 and logic dictates that it was an older crowd. I remember thinking it reminded me of a school cafeteria.
2nd mistake - seating for 2. With six, we were at a section of table at the back that was for 6 or 8, but we had it to ourselves and felt a sense of privacy. With just the 2 of us, we were sandwiched between other groups, and directly next to us was a family with a 1-year old and a 4-year old who were NOT enjoying themselves. The parents were whining at the waitress, who we could tell was losing her patience with them, and the little boy was coughing open-mouthed in our direction (including on the food) throughout the meal. It was his birthday (they call people with celebrations up on stage, so that is how I knew), and I could have said something but chose not to.
Instead, we snuck out before the show was over, and just rode the monorail and made jokes about the whole thing. It was a waste of close to $100, and we were convinced that the colds we came down with at the end of our trip was due to that. But, it made memories for us, and I can see that much of the negative was circumstantial.
We hear rumors that the Luau may not be around much longer. In fact I think it may be down to just one seating, not sure. If you thought it looks appealing, and since you are not shooting for a romantic couple's dinner

, you may very well like it. Many do!
Good luck with your decision and have fun.