What initially begins as a pretty interesting thought experiment about small groups of joined minds and experiences under a quantum entanglement surgery quickly becomes a lot more. 
 Doesn't it sound interesting when it quietly becomes a murder mystery, a philosophical discussion about immortality, including mental illness, meme propagation, obsession, and later, a myopic cautionary tale pitting the Joined against the Solos and eventually even a fascinating evolution of humanity as it reaches for the stars? Yes? :) 
 And that's just the surface, because we get to know some rather good characters, and plot actions, too. :) 
 It's an immensely readable near-future hop that gets progressively dystopian while retaining the very interesting core concept as both the center piece and the conflict, both within the other joined and with the rest of the solos in the world. 
 Honestly, this could have been fine as a novel that had just focused on just the smaller plot actions of the first half, but I feel quite lucky that the author decided to put a lot of extra thought and effort into the whole concept, discovering and exploiting a lot of the more interesting aspects of becoming an effective immortal by constantly changing out the "drives", or the individual people, as they wear out, and taking it much further with nearly crazy meme-sets caused by expanded join-sets. 
 I love SF and Fantasy that show us the rules, and then show us how to break them. This novel certainly gives us a fascinating ride. :)