UnRarX is a RAR archive decompression and recovery tool. It is a very basic app that can be used to extract files from RAR files. It doesn't support any other formats. It is extremely easy to use this app. All that you really need to do is drag and drop a RAR file onto the app's interface and UnRarX will automatically extract the archive's contents to the same folder.
The application doesn't really have any advanced extraction options. You can't automatically delete the archive files after a file has been extracted. The only option you really get is keeping broken files after extraction. The output folder can be changed at the top of the application. By default it is set to extract to "same folder", but you can pick any other location on your Mac.
UnRarX supports the PAR2 standard for recovering files. Besides extracting and recovering files, you can also test .RAR files without actually extracting anything. There is support for password-protected files, as well.
All in all, UnRarX does a good job of extracting RAR files. It is fast, and I like that the interface provides a log of all the tasks that it carries out while extracting. However, its limited format support doesn't help at all, while there are other free apps that support them all.