Answered by Robert Halligan
A. Thankfully, ISO/IEC/IEEE 15288:2015 is hugely better than ISO/IEC 15288:2008, so a lot of the comments on the 2008 standard do not apply. I would rate the 2015 standard overall at about 6.5/10, more good than bad, but still with some serious issues.
The main problem with the 2015 standard is the absence of recognition of the concept of a capability system, and the essential problem definition/problem solving relationship between requirements at a capability system level and requirements on solution elements including bits of technology (what the standard refers to as “system requirements”). The consequence is an implicit “then a miracle occurs” process, together with duplication of what are in reality identical processes of problem definition applied to different systems.