When you empty the Collector you can now choose Move to Trash instead of deleting permanently, so you can put things back later (#17).
New Back and Forward buttons, like Finder (#13). Back goes up one level and Forward returns to the folder you just left. Use ⌘[ and ⌘], your mouse's side buttons, or a trackpad swipe. Unmount moves to ⌘E.
Rows in the list highlight on hover again, and the Collector popup no longer stays open, after a quick drop onto the Collector (#18).
The saved scan no longer keeps growing after repeated rescans, and saving it is faster (#14).