Just to note, WordPress uses x.y.0 for major releases, so this is no more of a major release than 3.9 or 4.1. It's an awesome release, but don't think of it as "major version 4". :)

Congratulations to the contributors on a fantastic release.

Interesting to see WordPress (the software) to evolve better in a new world of competitors like medium, svtble, vix, squarespaces, tumblr etc.

The fine balance between the hosted (Wordpress the SAAS) wordpress.com and the open source version running in thousands of hosting providers still works with no big problems.