This is a very important milestone release. It features the new config parser and thus provides the basis for a more intuitive config format. With 6.3.3 there are already some enhancements to the format. However, more changes will come up with the next minor releases. For details, please check this link:
It is worth noting that the performance of script-based filters ("if … then") has notable been improved. Preliminary benchmarks show an improvement of at least a factor of three (more detailed benchmarks will be done after the new scoped object statements have been introduced).
We would appreciate early adoption of this release. One goal in releasing it is to see if the new parser actually is able to handle all legacy configurations found in practice (note that the parser was written from scratch).
As always, feedback is appreciated.