I read the website before the book existed. Actually, I argued that it should be turned into a book, because books in general have higher status than websites. Then I read the book, and translated it to Slovak language.
My opinion on reading the comments is... they are interesting, but the added value per minute spent is significantly lower than reading the book. (Some of the comments are awesome, but most are not, and there is a lot of them.) Thus, if you have anything useful to do, reading the comments after you have read the book is probably a waste of time. (Perhaps, if you have specific questions or objections to specific chapters, you should only read the comments in those chapters.)
Your time would probably be better spent reading high-karma articles which are not part of the book (is there a way to see the highest-karma articles? if not, look here), and... you know, going outside and actually doing things.