Maybe if you haven't read any other philosophy, theology or science books then this will be a highly thought provoking book. But people have been thinking about these issues for millennia, and I don't really see that much significance can be given to one person making up a lot of stuff without reference to earlier work.
Adams says that the book shouldn't be read by under 14's. Well, the book does have a lot of socratic style argument - showing that people don't really know what they're talking about - and Socrates was sentenced to death for corrupting the youth of Athens (I can't say I'm really surprised - it's a very annoying style of argument). I guess that Adams wants to avoid a similar fate.
Note this book can be read online for free at http://www.andrewsmcmeel.com/godsdebris/