I have been visiting this place on and off since before 1991 and I think this is a very good place to take young children. I know that my daughter (who normally got bored with museums) enjoyed it in 2000 at the age of eight). I enjoy just going and renewing my knowledge of the area from when I use to live there in late 60's, 70's, and early 80's.
Not much to say about it except it is free, and while it is getting a bit yuppie on the environment stuff, it is still a nice place to visit (and there is an elevator for those stair challenged folks). Take part of the day and go see what the Channel Islands have that most of us concrete jungle folks do not see, except at a distance.