There's nothing more frustrating than having to rename several files at once and then finding that you have to go through them one by one.
Mass Renamer allows you to change and rename files easily and quickly but not just that, it allows you to change some of the information contained in the document properties. It's particularly useful if you've been in a position where your files have been deleted and you need to restore them to their original state but don't have enough time to go through them all separately. Mas Renamer goes beyond renaming just file names however and also allows you to change whole directories (including subfolders) in one step. You can define rules for file changes and setup complex tasks to be carried out automatically while you are away from your PC. The problem is that this program seems mainly designed just for changing documents rather than other types of files. So for example, you can change documents according to Keyword, Template, Last Author and Revision History, but you wouldn't be able to change music or multimedia files.
A useful mass renamer but only for those that are editing mainly documents and need to search by a specific key field.