Changing Style Mid-Series

I’ve been reading a very well-known science fiction novel series, and I’m now on the third book.  I have a problem with this series.  The first two are great.  I really enjoyed them.  But this third book has completely changed in style.

I’m only about 160 pages into the book at the moment, but it seems as if the main character is now just some background character who has had a single chapter written about him. He was the main character in the first book, which was full of action, and was a sympathetic character.  I felt like I was in his mind.  The second book takes place when he’s an adult, and it was again about him going through a difficult problem, trying to solve it.  There was less action, but the story was full of mystery, and the character was as formidable as he was in the first book.  Now, I’m not sure what to expect in the third book.  He hasn’t played much of a part, and the part he has played has been rather uninspiring.

The major change that has happened is that the pacing is completely different.  While the first two books were quick reads and a lot of tension, this third one is all about philosophical discussions.  It’s all philosophical it seems.  While that may not be a bad thing if it were a standalone book, it feels like it has completely taken the spirit of the series and smashed it to pieces.  I don’t feel the urgency and tension from the first two books.  Now I get chapter after chapter of characters deep in philosophical discussions, arguments in their own minds, and a complete lack of any kind of action that made the first two books very enjoyable.

I don’t mean this to be a review of the book, as I’m only a quarter of the way through it, but I felt like I had to say it.  I won’t mention the book, but you can probably figure it out.

How do you feel when a book in a series takes a completely different writing style?