(I know there could be some mistakes in this review. I’m trying to improve my English, thanks)
I assume there is little I can say about this book that has not already been told. My fault for not reading it earlier.
Anyway, a short comment. For me, the achievement of this book is to very cleverly mix a wonderful sense of humor with some tropes of science fiction (such as galactic empires from space opera stories or also artificial intelligence), in a way that may seem like a light reading but that actually contains some bold insights. For example, a resource that the author uses is to show our tiny human problems on a galactic scale, which helps to put everything (philosophically) in perspective. So, in this book, we, the humans, in our unconcerned planetary isolation, understand little of what goes on at the galactic level, including things that can affect us, let's say -ahem!- directly.
So Douglas Adams invites to ask ourselves: What if our beloved and also mistreated planet, often treated as the center of Creation, was just a minuscule curiosity in the galactic order?
I've been told not to bother reading the sequels so I'm keeping the good memories of this one.