I've been using this app for a while now and is by far the best one I've had my hands on.
There are some things I miss tough (that I haven't found in any other application as well).
I've put down a list of things I miss while trying to edit the tags for my +/- 2000 albums.
An option to automatically search for cover art in the same directory as the music is in. Make a list of it where you can select which ones you want changed instead of manually selecting the music and browse for the cover art yourself.
When editing tags in the list, save the changes temporary somewhere so you don't have to click save every time you edit something. There should be an option to save the whole list after you're done.
Make an option to auto tag files according to the directory structure. I have my albums in /Artist/Artist - Album/ this way I could automatically change the artist and album in the tags.
Maybe make it possible to search online for cover art automatically for a bunch of albums.
That's about it. The rest is great, thanks a lot.