From MJ v8.0 Help file:
Better Organization. Faster, easier and more powerful file organization
Send To bar. Used to easily add files to a playlist, to Playing Now, or even to a device. Double-clicking on files will automatically send them to whatever destination you have chosen.
More flexible Media View. Now you can customize Media View to include custom fields, file location, and playlists, among other things
Simplified Interface
Inline File(s) Property Editing. Edit all fields from the content view.
Support for CD and DVD Database
Integrated CD Labeler Media Jukebox now has it's own labeler, that will automatically fill in fields for you.
Visualizations. Highly improved and customizable visualizations.
Visualization Studio. Create your own visualizations with this new tool.
New Freeform "mini-me" Skins. Media Jukebox now offers new "mini-me" modes, with it's own skins.
Expansive Id3 Tag Support. More flexibility with tagging. Can now remove tags, and save all fields into extended id3 v2 tags (including replay gain, custom fields, and rating)
On-the-fly Encoding