Simple:Press 6.3.0 is almost ready for release but it needs to be tested on some real-world sites first.
If you have a staging site and are a Silver/Gold/Platinum customer please contact us for a beta copy along with updated versions of the plugins and themes.
If you're not using any of our plugins, you can also take the beta out for a test drive.
The more users that install the beta, the more stable the final version will be. At the very least you should install the core plugin so that you can become familiar with the new admin UI.
And, if you do not have a test or staging site, now would be a good time to have your host create one for you. Every website needs a staging site to test plugin and theme updates before installing them on a live production site.
Along with the new UI, this update includes a couple of bug fixes and tweaks.