Well, now you can also add exceptions to the rules by adding or removing individual songs from one or multiple smart playlists:
In the playback control for the now playing title you can open an extra dialog where you can add ⊕ the now playing song to one or more lists (A, B, C, ...) or remove ⊖ the now playing song from one or more lists. Each list button cycles from "no exception" to "include" and "exclude", e.g. "A"→ "A⊕" → "A⊖" → "A".
In the above example the song "To Kutsavaki" is set to be excluded from list C and included in list F. When list F is reloaded, the selected song will be added to the result set and marked with "⊕":
These exceptions (includes /excludes) are only applied when the corresponding list is reloaded (with ⏎).
They appear as a new "rule" which can be edited:
So, whenever you are listening to a special song you like, you can now simply add it to a playlist of your choice without having to adapt the rules of this list. Likewise, if you dislike a song, you can quickly mark it for delete and with the next reload it will be removed.