The Zuiderdam, as with all HAL ships, seem to be geared to the older crowd. That being said, my wife and I (48 and 56) had a great time. The disco gets going later in the evening after the shows when the old folks go to bed. We sat with the DJ waiting for more fun people and had a great conversation and got "primed" for the fun. He was open to requests. My wife got things really going with the electric slide and it just got better.
I believe the key is to have fun and don't wait for others to make the fun for you. We did and are going on another HAL cruise in November and again next year sometime with a RCL thrown in for good measure.
I posted a review of our 6 March 2004 cruise on the Zuiderdam 3 weeks ago but I guess Tom wasn't impressed "cuz it ain't showed up yet".
Great ship, service and food. 9.9 out of 10.