One thing that bothered with with the plot is that the children would be so stupid. First, the learning capacity is at its peak at childhood. Given how old some of these kids are, it's surprising that none of them became genius. In addition, it is proven that in situations of need, children can learn to become quite responsible when they are left to themselves. So the immaturity illustrated in the kids here is rather improbable.
The other thing I did not buy was that the planet was exactly the same as Earth. Come on! What are the odds?!
That being said, this is a pretty good sci-fi story. I liked the team work to find a solution and McCoy particularly shines in this one.