I'm going to get a lot of people disagreeing with me, as usual.
There are three science-fictions series where I think the first (and sometimes the second) book in the series are brilliant, but each succeeding volume gets progressively worse.
I think the reason for this is that the writer forgot what made the first book(s) good.
DUNE, Frank Herbert
STARTIDE RISING and UPLIFT WARS, David Brin
ENDER'S GAME, Orson Scott Card
All of these books are great and I highly recommend them to everyone.
But most of the following volumes quite frankly suck.
How can this be?
In each of these books, the authors were lauded and lionized and given awards. What did the they take away from this?
They heard the message that the "ideas" and the "philosophies" and the "world-building" was what made these books special. And don't get me wrong, they are very good in all those elements.
But what really made these books good was that they had great characters that you cared about. As detailed and careful as the authors were about their world building, the stories really revolved around characters.
The later books are mostly about ideas, and the characters are just there to expound.
And in my opinion they are nearly unreadable. The second and third books are OK sometimes, but after that....yuck.
4 days ago