In reply to chuck.

Chuck - It's not just the speed that's new here. It's the potential to do some really interesting functionality behind the scenes while users are browsing your site and more. 10up has done an unbelievable job with http://wamu.org/. It's a react-powered WP site with a full podcast bar built-in at the bottom. So you can listen to a podcast and browse the site at the same time. You can read more about it here, https://10up.com/blog/2016/wamu-react-rest-api/. This is the future of WP in my eyes.