Wayne said in https://lists.launchpad.net/kicad-developers/msg41442.html that 5.1.3 will be released soon. There will be quite many bugfixes so if you have encountered any bugs in a previous release it may be beneficial to update as soon as it comes available.
One way to find out what is changed is to use milestones in the bug database:
although there may be even more which didn’t have this milestone in the database. There are over 100 bugs listed!