I found the sound quality iof this product very good. Also I havent had to retune in new locations as yet.
The web site says it will handle 99 folders and 1999 tracks.
Actually it will hold well in excess of 99 folders - I checked it up to 400 folders. However the folder number displayed on the Soundfly is only correct up to 99. Over that number, it displays a dash in front of the 2 digits. So folder 101 displays as ,d01 and 201 also displays as ,d01.
The folder number does not display via the car RDS/tag system.
With regard to the capacity of music files, the Soundfly displays correctly up to 1999 - however it seems to hold and play in excess of 9500. But the first digit can only display as 1, so eg track 2031 displays as 1031 etc.
The track number displays correctly via the RDS/tag system.
The folder ordering is also quirky. The RDS/tag system displays track number, artist, and track title. But it doesn't display the album name. It orders by top level folder name, then by second level folder name etc as you would expect. However, it appears to order the shallowest folder depths first, and then the deeper ones after. So B/your_tracks, is before A/Ayour_tracks.
Safest bet is to maintain uniform folder depth, eg Artist/Album/Tracks
Would be 5* if had better display