It provides a nice interface for managing and editing tags that integrates well with other command-line tools and keeps your file system well-organized/up-to-date as you edit the tag contents. The batteries-included integration with datasources like musicbrains and discogs is nice, but, at least for me, beets is mainly a better tool for accomplishing the same tag and file janitoring I was doing with things like foobar2000 and eyeD3 a decade ago.