WildFly 20 is primarily focused on bug fixing but there are some new features in the security and EJB areas. The full release notes for Beta1 are at [1]. The issues resolved in the WildFly Core releases that went into Beta1 are at [2], [3] and [4].
Please try it out and give us your feedback! We're aiming to release WildFly 20.0.0.Final in just over two weeks.
Best regards,Brian