The novel of Revenge of the Sith is canon. It aligns with the established Star Wars canon framework and adds depth and detail to the events depicted in the movie of the same name.
One of the best quotes is 'This is how liberty dies... with thunderous applause.' It shows the tragic irony as the Galactic Republic falls while the people, unknowingly, cheer for its downfall.
The plot of Revenge of the Sith centers around the final stages of the Clone Wars and Anakin Skywalker's descent to the dark side. It's a complex and intense story with lots of action and drama.