A very disappointing book. It has a lot of pages but no opening is covered in anything like real depth.
It tries to show how games develop beyond the opening, which is admirable, but often these games proceed way beyond any relevance to the position that came out of the opening and the type of play that is characteristic.
There are also enormous gaps in the coverage with no mention of almost all the main lines in openings such as Sicilian Najdorf.
These ommissions combined with very poor error checking (in some cases 1. e4 appears when it should be 1.d4) mean this is not a book I'd recommend to anyone. Not because it's THAT bad but there are much better books available.
If you want to buy a 'fat' openings book, buy Nunns Chess Openings which is in a totally different class. NCO is very comprehensive, up-to-date and the condensed text which introduces each opening gives a much better overview than Schiller's work. But then NCO is authored by three leading grandmasters, among others ...