We went on a Tuesday so our kids (7,3,and 1) were free with adult tickets which were $14.95 each. They force you to take photos as you walk in so you can buy them in the gift shop at the end which was annoying. Once we got inside it was great! My three year old loved the touch tank and all of the exhibits are really designed for smaller children. Everything is at their height and very hands-on. My one-year old was a little overwhelmed but eventually warmed up to the environment.
The biggest complaint I have is that we arrived right when a daycare field trip arrived and it was insanely loud. We actually went back in a second time (the pass is good all day) after the daycare group left and it was mush more enjoyable. Very relaxing and easier to keep up with the kiddos! I recommend you make a day of it, shopping, eating in the food court, riding the carousel and mini-train around the mall. I heard there is a Lego store there too but we never made it there. There is also a go-kart track outside but it was way too hot for me.
I probably would go more if it was less expensive but it's still a good place to visit once in a while.