Taken at face value, as a kind of fantasy thought-experiment succintly exploring the sheer strangeness of the concept of death itself, the book is by turns witty, imaginative, playful, and occasionally poetic. Each tale works independently in terms of its individual logic, and overall there is a real cumulative pleasure taken in the notion of comparing 40 'invented' afterlives. Some of the ideas are extensions of already existing fantasy and science-fiction lore to some extent, and religious ideas also get included - paradoxes and all - but what becomes clear,as it should, is that all of this is about how we actually value our lives, and really has nothing to do with the afterlife at all. It is essentially secular in its free play with ideas, levelling the profound alongside the trivial, and the 'deep' with the light.
Apparently some religious critics have found this book shallow and undermining of the seriousness of certain religious ideas. As someone who firmly believes religious afterlife 'hope and judgement' conceits are human-foible infected fantasies anyway, I find the humanity and playfulness exhibited here actually a confirmation of one the best aspects of human nature - inquisitivity. God forbid Eagleman uses the imagination God apparently gave him in the first place.