Wow, nearing the conclusion of this one, and I really have to say the three sequels I found quite interesting. Very interesting about "machine intelligence," and the prescient discussion of terrorism, and I really was intrigued by the idea of an enemy race of energy beings who were trying to recreate the universe without matter.
And. . . spoiler below. . . ..
I was totally blown away how at the end of the third book you realize your friendly neighborhood narrator. . . has been dead the whole time he's narrating to you!