The migration guide is available in the PHP Manual. Please consult it for the detailed list of new features and backward incompatible changes.
The inconvenience of the release lateness in several time zones is caused by the need to ensure the compatibility with the latest OpenSSL 1.0.2e release. Thanks for the patience!
It is not just a next major PHP version being released today. The release being introduced is an outcome of the almost two years development journey. It is a very special accomplishment of the core team. And, it is a result of incredible efforts of many active community members. Indeed, it is not just a final release being brought out today, it is the rise of a new PHP generation with an enormous potential.
Congratulations everyone to this spectacular day for the PHP world!
Grateful thanks to all the contributors and supporters!