Hello!
Probably DO haven't column setting for displaying MP3's Rating like default Explorer does.
If it really doesn't exists hope developers will add it next release 
Hmm, on the other hand, my music collection contains only music of the highest rating grade. Why should someone keep music rated with only 1 or 2 stars? 
Most MP3 player can play music by rating state, and don't know tag Mood.
And you can sort your music by moods via rating tag
This is one of the example. But anyway, if Windows Explorer can show Rating column, why Opus can't