It seems that the comments and the ratings are stored only in the database.
This is not convenient. Why?
Sometimes album folders should be renamed or moved to another subdirectory (i use genre based subdirectories for prefiltering). So the comments and ratings are lost. This is really annoying cause writing comments on a bigger collection is lot of work! Besides i'm little bit sceptical about database migration between different versions of subsonic.
Maybe it is not much additional work using a (human readable please!) textfile for the comments on each album folder? Just like the "folder.jpg" for the album art there could be a "comments.txt" for the comments. Maybe the ratings could be stored in the "comments.txt" too or in another file. Or maybe you can store the ratings in the tags on each file. But please do not store it in the DB.
Thank you!