Perhaps this has been mentioned before. However, when reviewing my tags or self entering them, I pay particular attention to creating accurate genre and subgenres on my tracks. As a DJ, this is important and genres can be quite personal (An Auto Tag of 'electrionic' is very vague for example)
One REALLY handy feature would be to be able to play and search through the track, so that I can get a feel for the genre and set it. It would save tones of time, rather than doing it on an external media player.
Perhaps a little media player section, even with just a simple track bar?
Let me know if you think it's just overkill for most people's needs.