This release incorporates new features, such as the CAKE network management to mitigate bufferbloat, so that bandwidth can be maximized even in the slowest ISP links and routers. It guarantees a minimum I/O latency targets for cgroups, it has experimental support for the future Wi-Fi 6 and optimization of memory consumption for overlayfs users.
It also includes an EROFS experimental file system optimized for read-only mode, a new asynchronous I/ O polling interface and support to avoid unintentional writes in a FIFO controlled by an attacker or in regular files located in sticky directories.
In addition and as usual in each new version, improvements in hardware support, virtualization, file systems… have also been added.
Check the full list of new features here: Kernel Newbies.