SPM syllabus covers concepts both in depth and in breadth, I studied triple sciences and relied heavily (and primarily) on Oxford Fajar's reference books, I then browsed O levels/GCSEs reference books and have no problem understanding the syllabus which covers everything we covered. The only reason people doubt its legitimacy is due to the weak execution. Example: the SPM exam questions are pretty straight-forward with minimal emphasis on the application of the knowledge. The grades are often lowered (drastically) following the normal distribution graph, where you'd normally need 90 marks to get an A+, the marking grade is most definitely lower than that, don't even get me started on the passing mark.