That about matches with my recollections of the book: packed full of information, but dry even for a GURPS supplement (which was a problem with their entire 3rd ed. Traveller line, <abbr title="In My Humble Opinion">IMHO</abbr>). When I sold off all of my GURPS Traveller stuff it was one of the ones that I actually contemplated keeping due to its comprehensiveness.
(For those looking for a second-hand copy, I'd suggest keeping an eye out for international auctions on eBay; because international shipping rates scare people off they often go for less than US auctions, even once the increased shipping is factored in.)
With that aside, one question for anyone who knows: I recall that the printed version had a bit of an errata problem. Do the <abbr title="Steve Jackson Games">SJG</abbr> PDFs merge the errata into the text, or is it like the printed copy in that there's a page at the end with all the corrected page references?