• Critical path scheduler which orders the jobs by their runtime history #2177
  This may break your build if you haven't specified your dependencies correctly.
• Resiliency against inputs changing during the build #1943
• Reliable ETA and progress percentage in status #1963
• Support for path lengths over 260 characters on Windows #1900
• ARM binaries are now available for Windows and Linux, too
• Several bugfixes

See https://github.com/ninja-build/ninja/milestone/6?closed=1 for a complete list of changes.