The search box is a great addition. Haven't tried the movie preview yet (I predict it to become a HDD space eater if we make movies for all games).
The only feature I would love to see is in the game details window (Shift-I). It would be great to be able to differentiate the ROMs that are in the current selected set from the ROMs taken from the parent set (e.g. ROMs listed in a different color or a note in the status column).