PQ has just put a long, thoughtful review of The Illuminati Papers up at his blog, A Building Roam. He does a really good job, as usual.
A few comments/reactions:
(1) I agree that it's one of RAW's best. I suspect that's because it's the first book that collects many of
RAW's short pieces, and he had a lot of good material to draw on at that point. Email to the Universe, RAW's last book, apparently is strong for much the same reason -- Mike Gathers and Company had gathered a lot of good pieces on rawilsonfans.com, which the book apparently drew on.
(2) PQ says this is a "perfect companion text to Prometheus Rising." That's true, although I've always thought of The Illuminati Papers as an extension of the appendix in ILLUMINATUS!
(3) PQ remarks, "Many of the essays have bylines showing the name of characters from the Illuminatus! novels but, the more one learns about RAW, the more clear it becomes that these are all written by him. Again, I wouldn't be surprised if those bylines were a late addition. (They seem pretty convoluted if you ask me.)"
I can confirm that's true in at least once case; the essay published as "Neuroeconomics" by Hagbard Celine was pubbed as "A Few Blunt Statements About Neuro-Economics" by Robert Anton Wilson in "No Governor 4."
On the other hand, ILLUMINATUS! has material in the appendix attributed to Hagbard Celine. Wikipedia says that The Illuminati Papers has new and collected material, so perhaps some of the bylines in TIP were present from the beginning.
Arthur Hlavaty's review of The Illuminati Papers is here.