Example 1. Album art.
When I play anything I haven't played for a couple of years, the artwork often changes:
1. Randomly (i.e. not always)
2. Sometimes to a completely different, irrelevant album - e.g. The Flock by the Flock becomes Flock of Seagulls by A Flock of Seagulls
3. It does this in a manner where Time Machine thinks the file has changed but, for example, the modification date in Finder is unchanged.
Example 2. Play
Play Next - adds track to top of playlist
Play Later - adds track to top of playlist
And the difference is ...
Example 3. Ratings
Complete confusion through the app between track ratings and album ratings. So, I never set album ratings but when I play a few tracks the unplayed tracks set assigned a rating (grey not blue). Screws up smart playlists