Hyperion - Dan Simmons
(read originally in 1993).

The details of the technology or the scientific credibility in a SF Book are not the main flaw for SF writing.

I am a computer scientist and I read the Hyperion Saga long ago, but the more persistent elements that these books left in my memory are not related to the quality of the scientific background:

1 - The sole idea of the cruciform organism and its curse of endless life was already very attractive, but it failed miserably.

2 - The shrike has a very weird turn-around, becoming a protector although it was originally a baroque-awesome-evil killing machine. Deus-ex-machina... 

3 - Similarly the fate of the characters in this book was a bit wasted by the irruption of Aenea as a kind of saviour. Another Deus-ex-machina...

4 - Another thing that spoiled the series for me: The incredible flaws in logic. The 4-book-series is drowned in incredibly idiotic characters that just keep going, failing to prepare even when they have years to do so, they never learn, most of the time, they are just dragged along by events. Whenever it suits the author, the characters are smart and cunning. And when it’s too bothersome, they are as dumb as a lamp-post. We also have computers abusing the mental power of all of mankind but too moronic to get rid of a little paranoia? 

The book has a few good ideas, but it stops there. The technology is based more on magic than science. In a few odd places, the author starts to develop an advanced civilization but it only scratches the surface. 

Getting the basic science right is nowhere near the point, but it helps when the writer gets it right...