I did feel, with Life, the Universe and Everything, that the series was starting to lose it's way somewhat. With this book, though, Adams gets solidly back on track.

It's very different to what has gone before, and this is very much to the book's advantage. Arthur is more of a character this time around and there's visible plot.

So Long, and Thanks for All the Fish is still very much a Hitchhiker's book, but it also demonstrates the value in a series taking the occasional left turn.