I LOVE this app! I needed to move my iTunes library because it outgrew it's old harddrive. Because it is so massive (1-2 TB of mostly video) this is usually such a painful process. It takes forever, crashes in the middle (corrupting however many files were in progress), and gives you a super fragmented copy at the end.
With ultracopier, I was able to queue of the file move, every file got copied on-by-one, AND it just saved the new file right after the last one, resulting in a FRAGMENT-FREE 3TB harddrive (which would have been a nightmare to defrag after.
It works so well in this application, because there is no real deleting of files, and I believe if I don't have iTunes download multiple files, my drive will stay happy and clean even when I buy new stuff.
The only reason I dinged a half star is it is pre-launch and a little rough around the UI. However, it is a great tool, and I immediately donated $10 to encourage its future development.