This is the second book in The Galactic Empire series, and although it was a bit better than the first, this series is not nearly as good as the robot books.
Part of the problem is that we don’t get much of a sense of what has happened in the galaxy since the end of the robot series. There’s a planet, Trantor, that’s running a very large galactic empire. The number of planets is many times larger than at the end of the robot series. We don’t know much about these planets, so frankly I never really cared much when events unfolded. We also don’t know what happened to the spacer/Earthman/settler divide that characterized the robot series, though it appears the Earthman/settler side won. For whatever reason, robots seem to have disappeared as well.
In this book, there’s one independent planet oppressing another and the story is mostly of overcoming this oppression. Yawn.
Some rather bad scientific theories follow. There’s some discussion of Earth. It appears these advanced people of the future have very poor recording keeping, since they don’t seem to know that Earth was where humanity started. Science Fiction of the pre-early-internet days always seems to underestimate improvements in information technology. Anyway, the discussion of Earth doesn’t seem to go anywhere (I believe it’s setting up the next book).
To be honest, I’m glad there’s only one more book in this series before the Foundation Series starts.