I mostly looked through Book 1 since I knew that had changes. I just skimmed Book 2-1, which to a quick skim appears to be more-or-less the same as what's already online.
Yes, text updates are all there. The summer updates are in book 1.
Rob mentioned that he had to redo all the pages for book 1 because the original web version had text bubbles that covered too much of the art. I appreciate the thought, but personally thought the text ended up being a bit too small in the final product; I had difficulty reading some of the lines through (corrected) 30 year old eyes. I don't know how what Erfworld's demographic is, but I think age 40+ readers would start to have difficulty without a magnifier. (Klogs had nice big text.
I thought the quality of the book overall was ok. It's not far off from what I expected from the price. I wouldn't necessarily call it cheap, but the print quality was a bit sketchy (aggravating the text issue above). Art wise, I thought everything looked a bit too dark. The outdoor scenes are fine, but indoor and shadow scenes suffer the most, particularly the GK tower interior & tunnels.
I figure a hardcover/HQ glossy/omnibus edition of books 1-3 is just something down the road 10-15 years from now.
There are a number of bonus pages spread throughout. They are mostly action scenes that don't change the workings of the story, with one notable exception (page 159).
And maybe I missed it, but I would have liked an index of all the bonus pages. I already knew the story and just wanted to see what was new. When I feel the need to read it cover-to-cover I can log it myself, but that probably won't be in the near future.
I'm disappointed that "knight" was not in the glossary. It stuck out since the hobgobwin definition mentions possible promotion to knight, heavy or warlord and both "heavy" and "warlord" had their own entries. The archon definition mentions the term knight as well. So I'm left wondering what a knight is.
All in all, I'm happy. Though I do view it much more as a capitalist "dollar vote" than a pure product purchase. I kind of wonder how well it will be accepted by non-fan buyers.