This is more of a formatting issue than grammar or spelling, but this seems to be the best section to toss this in. Unfortunately I haven't had nearly the time I had hoped to read through the books so far, but the first thing I noticed was the formatting of the table of contents. I found them a bit cumbersome to navigate. The page numbers are generally bunched up with the text or are wrapped to the line following the text. I guess my preference for this area would be to have a more "columnized" presentation with the headings on the left and the page numbers on the right, possible in a slightly smaller font to avoid the wrapping issues.
~Travis