This is a collection of the three original books.

I found the book to be "dated": a style of science fiction writing that does not stand well to the passage of time.

The verbosity was extreme and mostly pointless: the good ideas in the book could have been rendered in a couple of hundred pages.

Many interesting plot lines were developed and then dropped.

The purpose of the verbosity is sometimes to develop a feeling for the surroundings and the future universe, but the book did not describe the kind of cities or dwellings (I have no idea of either), or the characters of the people, and none of the characters were convincingly developed.

If you are willing to slog through it, at about page 350 the book will become somewhat more interesting as the pace picks up for the second half, but it is still unconvincing writing.