I agree completely with Jessica about it being a little too difficult to keep track of my two kids there. They too go in separate directions and one ends up in the ride-on cars and the other ventures over the the arcade area. I never do it by myself, only when my husband or grandma can be with us to help watch. It's true there are 3 exit/entrances, and the play area is usually always busy, so when I can't see my kids for a second it makes me nervous.
They recently upgraded it a bit, they replaced the old climb-ons that were worn out and tattered, and added more smaller ones.
Maybe something you'd also be interested in...I had to take an orpaned squirrel to Lakeside Nature Center yesterday (right near the KC Zoo), and was pleased to find I could also take my kids inside for FREE to see the rescued animals there. There were bunnies, birds (eagles,owls,hawks), snakes, turtles, fish, opossums, and more. My kids loved it! It took us about 30 minutes or so to see everything, we took our time. But the kids loved it and it didn't cost anything so that might be something fun you could do with your son.