A bit unfair. In fact most of the SAP books unfortunately are a waste of money because 99% of the content just repeats the help on their webpage.
If there is something I would complain about, it is that their help pages are a convoluted mess of years of content with broken links galore, lots of duplicated content between help pages between different versions and an on site search which is just not very good.
So basically you have to Google stuff, then unfortunately come out on the help pages for an edition you do not actually have and then will have trouble finding the corresponding help page for the thing you actually run.