The premise of the story is God is building this huge new amusement park. Everyone is invited but, of course, not everyone shows up. Some stay home because they just can't believe God would actually build an amusement park. Some show up to protest the waste of electricity and other resources that the amusement park is doing. They stand outside in the hot sun without water despite the fact that God is the power of the amusement park. He is making the electricity, water, and other natural resources himself. That's the benefit to having God as creator.
However, when you get in, you notice something about those there. There are some who only want to explore certain parts of the amusement park. God walks up to these people and they start to argue with him as to weather there really is a roller coaster or a water ride. He looks at us and says that they'll eventually get there.
Then, there are other people walking around with maps complaining because things aren't in the right place or aren't as big as they thought the map made them out to be. God tries to encourage them to put the map away and just enjoy the place but they've become so fixated on the description that it prevents them from actually having fun there.
Then there's the majority of people who walk around saying things like, "I always hoped for something like this!" and "Oh my gosh! Did you try the one with five loops in a row? That was so fun!" and, "Did you make it over the bridge? There's a whole other part to this place. It just keeps going and going."
Then God would take the reader and explain that the amusement park represents his love. There are those who refuse to accept God's love by sitting outside complaining. There are those who want to put limits on God's love, whether by their own intellectual limitations or because their interpretation of scripture puts limitations on it. And then there are those who open themselves completely and really accept God's love as God wants to offer it.
In the end, I think this is also an apt metaphor for heaven. I think there are some who will never go to heaven because they refuse to believe it exists. I think there will be some who will be disappointed in heaven because they read the books of Daniel and Revelation and have an image of the way God will set up heaven. I actually think it could be really funny to see Jerry Jenkins and Tim Lahaye (writers of the "Left Behind" series) following God around saying something like, "Um....excuse me Most High but...uh...er....this isn't the way things are supposed to be in heaven. As you might remember from the book of Revelation..." And God just smiles and wonders if they need to spend some more time in purgatory. And then there's the majority of Christians who are astonished by the way things go and are excited to watch it unfold.