I haven't tried this on music or regular files yet (I do have tons of dupes there, too), but I've been using it to clean out duplicate photos which are in random folders within an overall folder in which I have all my photos. Due to my "backup neurosis", I have multiple files in multiple locations, some of which have altered names, some of which had corrupted creation dates (repaired with A Better Finder Attributes, once I saw them in my Gemini 2 review panel). The photo folder is a mess!
Because running Gemini on the entire folder leaves me with a mile long list, I've been comparing some of my biggest sets of likely duplicates by individual folder. This makes the selection and review process more manageable. I LOVE that I can choose whether to find "similar" files, or exact duplicates (pixel by pixel comparisons), that it usually makes the right selections as to what to delete, that I can choose entire folders and subfolders and tell the app (with the latest update) to deselect or select the duplicates in those specific folders as a batch, that I can choose to save the deleted files to a folder, instead of the Trash for my ultimate review, and that I can automatically create Hard Links to files I'd like to find under multiple directories, without actually having to have the duplicates in there.
Also, I had to call Customer Service for a question. They're in the Ukraine - so it was 4am there. They answered the phone quickly, their English was impeccable, and the gentleman with whom I spoke was friendly, pleasant, respectful of my intelligence and helpful.
So far, I'm loving this upgrade! The ONLY two feature requests I'm making thus far are: 1) I'd like to see the ability to create symlinks instead of only hard links (as I use multiple volumes and move my files among computers), and 2) that I can still have it recognize files that somehow have different sizes (off by kilobytes for some reason), without having to have it find all "similar" files. Once those are in, my 4.5 becomes a 5!