I've visited Discovery World a number of times and the most recent visit confirmed my fears that its a bad museum. The place has very little identity - its lay-out is confusing and many of the larger exhibits are rather boring and poorly designed.
There is a small aquarium which is fairly interesting, and the suspended ship is worth seeing. The rest of the exhibits are either poorly conceived or boring. As an adult interested in science and technology, this museum leaves me confused and a little angry.
The endless stream of schoolkids seem to enjoy the place, but don't go out of your way to visit. I hate to say it, but go straight to Chicago instead and visit the Field Museum, Science Museum or Shedd - Discovery World is a very weak contender to nearby heavyweights.