I've been auditing ISO 9001 standards since 1989. The 2015 version, in my opinion, is a step backwards. There is no mandatory documentation required, no quality manual, calibration traceability to national standards is no longer mandatory, virtually any clause can be identified as Not Applicable, no management rep is required, and top management is not clearly defined.
I was and remain extremely disappointed with the 2015 version. It took us 25 years to get to the 2008 version and it's all for nothing.