The first part of the show is no more lame than HDDR! The second part has real dancers demonstrating real talent and ability! And, even in the first part, there are some hunky guys to watch, so I'm not complaining!
I think show and dinner are approx 1 1/2 to 2 hours total as I recall. I agree the volcano dessert wasn't very good, but the rest of the meal is pretty good (edible anyway, which is more than I can say for HDDR!).
Overall, the luau compares favorably with luaus we've done on Oahu, Maui and Kauai (and WDW's is less money), although the location can't compare to a beach in Hawaii with the sun setting. But, if you want a Hawaiian tourist experience without the trip to Hawaii, it's fun and enjoyable. We'd do it again.
Our boys (11) prefer HDDR and its slapstick humor. The adults prefer the luau.