My daughter (age 11) and I just returned from a 7 night HAL cruise of the W. Car. (11/15-11/22)
It was my first HAL cruise in 12 years. I was amazed at the outstanding children's program on board. There was a large childrens area spread divided into multiple age/activity appropriate areas: An arts/crafts, toy area appropriate for small children, a gaming area for children of all ages with large screen plasma TVs with Wii, xbox 360 systems, a lounge are with video jukebox and hip furniture and a large outdoor "oasis" with a waterfall, small pool (very small, think very large jacuzzi that seats 12 or so).

My daughter LOVED the activities. She was there every morning and evening (cutting out of dinner a bit early so that she would be there at 7pm on the dot). There were ship wide scavenger hunts, contests, art projects,etc and contant game options with all the eletronics mentioned above and a huge selection of traditional board games. They were given tshirts and bags to decorate. Trays of snacks were served regularly. All kids activities were free, included in the fare. Afterhours babysitting (from 10pm-midnight) was available at a nominal fee (I think $5 per hour).

We were on the Ryndam, which was sold out--but there were only a total of 17 children on board (although we were told that the following week-Thanksgiving- they were expecting 175 kids). There were two full time staffers in Club HAL, both young american women who were charming, fun and involved in the activities (not just setting them up).
Because there were so few children, most of the crew were aware of my daughter and chatted her up whenever they saw her. Wherever I went onboard, crew members (and other passengers) inquired about her.

Overall, we were very pleased with the experience. Next time, I intend to take my 6 year old as well. I hear the other lines have better children's programs, but I wouldn't hesitate to book HAL with kids again.