I heard about this story a long time ago, I first learned that there was a movie talking about it but I did not know that it was based on a book. I watched the movie and liked it but felt that there was something missing so I went for the book, and I have to say that it was really insightful and full of background stories that made me understand everything that was not mentioned or cut out from the movie.
To mention a few things that differ from the movie there is the first part of Louis' family in the beginning. Additionally, there is a small story about another breed of vampires who did not have the same abilities nor did they resemble his kind (They resembled Zombies more than vampires. They did not think. They were simply like the walking dead).
Furthermore, Lestat was present at Claudia's trial, it was he who called for it, which was not mentioned in the movie adaptation as well.
I also had no idea that Armand had a hand in Claudia's death. Her fears and attempts to warn Louis of Armand's cunnings failed. Same as Louis I admired Armand and looked at him as a person with high regard deserving respect for his wisdom and experience, yet in the end, he betrayed him, and Claudia's concerns were warranted and Louis should NOT have taken them lightly. I guess he was blinded by Armand's charms.
Lastly, the last conversation that Armand had with Louis before vanishing was one of the most powerful ones I read, I wish that was included in the movie. It shocked me to my core, knowing that he hid that truth from him yet even when Armand admitted, Louis felt nothing... Only coldness and a bottomless, eternal, emptiness...
A quote from that part I am referring to "You showed me the only thing that I could really hope to become, what depth of evil, what degree of coldness I would have to attain to end my pain. And I accepted that. And so that passion, that love you saw in me, was extinguished. And you see now simply a mirror of yourself."
That part struck me so hard that I shivered from its meaning and felts its weight as if I was in his stead!
What a masterpiece!