Message of alpha1 follows, beta further down
We're proud to release the first Alpha version of the 2.4.0 desktop client. Among a ton of refactorings we've done to stay future-proof, there are also new features like OAuth2 support, a better error view, more sharing features and better file manager integration.
We consider it quite safe to use (the auto test suites pass!) but we encourage you (as always) to have backups of your data.
We also provide a build in the 'testpilotcloud' theme. This is an independent themed client (using ownBrander) that you can use with a separate sync configuration. You can install both from here: https://owncloud.org/install/#testing-development
Please see the ChangeLog and download links on https://owncloud.org/changelog/desktop/
Please report any issues as soon as possible to us. Ideally here in the thread or directly on GitHub. https://github.com/owncloud/client/issues
As usual, thanks to all contributors.
PS: https://github.com/owncloud/oauth2 is needed server-side for OAuth2. Will also be in the ownCloud marketplace soon.