Here are a simple features that would make life a lot easier:
1) When using "Fill Properties from Filename", it would be useful if the dialog would show the names and/or path of one or more of the files affected, as a sort of preview. I find myself flipping back and forth between the dialog and the Tag Info window to figure out how the filename is laid out. You could show the path or filename depending on which checkboxes were ticked.
2) An option to refresh properties from existing tags. The situation I'm thinking of is when a Various Artists album has the Artist field set to "Various Artists" and the "Name Field" condenses the Artist & Track name.
eg:
Name = "Moodorama - Jazz Tip"
Artist = "Cafe del Mar"
I want:
Name = "Jazz Tip"
Artist = "Moodorama"
Right now the only way to do it is to Rename File from Properties using one template, then change the template and Fill Properties from Filename. It should be possible to just parse the fields directly.
3) Buttons in the action window to shift to the next and previous file in a list. This would simply repetitive tag editing tasks. Eg. Make changes to a file and click "next" rather than going to the list and moving to the next file.
4) And the bigggie: it is very difficult to edit long smartlists within the bounds of the search box. For example, I have long smartlists that include a Media Type, select Genre, Randomize sort and Limit total size.
I frequently have to adjust the size limit to fit things on iPod, however that modifier is at the end of the smartlist and not visible. So I right click on the smartlist, Edit by Typing, and then use the arrow keys to scroll to the end.
It would be great if there was a Wizard interface - or a view in the action window - that allowed for smartlist editing with all the parameters in full view.