The Ultimate Hitchhiker's Guide

These books are not plot driven, and this is intentional. But for me is hard not to consider this as a negative.

First book and second book don't suffer from this problem, characters are strong, there is an overarching thread of inquiry about what is going on in the universe, all very enjoyable to follow.

Book three was ok.

The fourth books stands on its own. The story finally got closer to one character, and is mostly linear, yet an unsatisfactory explanation is given for the lack of continuance from the previous book's events.
The main plot is not at all original, yet it's still worth reading because Adam's wrote it. However there are original bits here and there in the classic style of Douglas Adams. I loved that the author addressed the the reader directly. Probably my favourite book of the collection. It was very interesting reading the foreward explaining the situation in which was written, makes it more valuable to me.

In the fifth book the cozy situation produced from the previous book's plot is abruptly, and again unsatisfactorily, truncated.
The story starts with a character that is only mentioned only in passing in the previous book. This last book uses the narrative tool of multiple realities, which is ok in itself I guess, bit I didn't like.
The whole plot is completely unnecessary. Really liked the ending though, but the premise of jumbled up realities and plural sector doesn't hold.

The book is sprinkled by some genius standalone scenes that sometimes return, even if only mentioned. Overall a worth read.