In broad strokes, this book seems similar to all the other Hitchiker's Guide books, and the author should be praised for following the same sardonic humour and expansive wit that Douglas Adams was so known for. However, it isn't written by the Adams, and by about half-way through the book, you can't avoid this feature in the writing. There has obviously been a huge amount of effort to follow Adam's original vision and story-telling style, but there are enough discrepancies and differentiation from the original that it become noticeable, in much the same way that the copy of a famous work of art can't exactly replicate the author's minutiae detail and brush strokes no matter how hard they try. In essence: there's something gone missing, not necessarily in the story itself, but the way
it was told, and honestly it was a struggle for me to finish this book with that obvious fact becoming more and more glaring with each passing page.
Now obviously, it shouldn't be expected for Colfer to replicate Douglas Adam's writing. That would be a ridiculous expectation, and it would make less than no sense, especially considering the penchant each writer has for their own signature, style and individual determination of the story itself. But when you're following this kind of series with what is essentially the finale, that excuse is scrutinised. This is not fan-fiction, this was published with the intent to finish what Adams started and... it struggled with it. In itself, this is not a bad book, and if I took it as completely separate from the series itself, I would call it very good and enjoyable, but it was created in the context of the series, and I don't think it quite fulfilled the demands made on it.
There tend to be two rather severe views on this book. One says that it was the perfect ending to this series, that it did all that was demanded of it and more and that no one can fault Colfer's continuation of Adam's work - and judging by the current page on tvtropes, that tends to be more the general consensus leaning
among tropers. On the other hand, you have those who label the Ruined Forever
stigmata with a branding iron, saying that it was much the same as a 5 year old tracing the Mona Lisa in crayon. What you think of this book is very
much up to your own interpretation. For me, it was only ok, no more or less.