Mostly a waste of money
As some other reviewers put it, this software works fine, until it doesn't. Generally it is very unpredictable, and will work fine for a while, after which it will give you the message that the DRM removal failed even for the same books that could be decrypted only a few days before. Usually following their instructions of how to make it work is to no avail. I would recommend to prospective buyers to look elsewhere for another DRM-removing option, if it exists.