The material is hard to read, for a number of reasons. More elementary or foundational parts were relegated to the EGA series of Grothendieck and Jean Dieudonné, causing long strings of logical dependencies in the statements. The style is very abstract and assumes that intensive use of category theory ideas is within the reader's comfort zone. An attempt was made to achieve very general statements (in particular to remove finiteness conditions, such as Noetherian hypotheses, considered 'parasitic'). The geometric motivations were known to the participants, certainly, but are not easy to connect to the words on the page. Overall, innovation was taking place on a grand scale, but only the experts could see how to localise it and apply it to problem solving.
The material was not refereed in the conventional sense. This led to a discreet controversy, after the ultimate proof of the Weil conjectures was completed by Pierre Deligne. He received a Fields Medal, but only after a delay of one occasion; it was argued in the IMU committee that the proof depended on material in SGA7 that had not been subject to the normal peer review process.
The subdivisions of the series were these: