Yes I did take a brief look at it, though honestly it's not something I personally am likely to use.
Looking at it again, I see a couple of problems:
1. Why are you creating black bands when resizing images? I think the images would display faster on Rockbox without them.
2. screenshot here
a. If it's empty, why not just say "Folder x is empty"? "Folder X contains:" and an empty list looks more like the program is broken.
b. You ask for confirmation to delete, but there's only one button, which scarily looks like it means "yes".
c. The folder is not actually deleted.
3. The "Update cover.bmp files" function.
a. Also asks a question but only presents an "Okay" button.
b. There are likely to be a lot of files to convert. Popping up a dialog box for every one will be very annoying. I think a much better way would be to populate a grid with the potential files to convert, similar to how QtScrobbler works.
4. The multiple windows ("Album art", "Pictures", "Pictures gallery") are useless, since you can only use one at a time. They should either be non-modal, or the windows should be converted into tabs in a single window to save screen space.