And it probably does a good job at it too, most likely interfacing I guess with the built in command line Unix utilities already built into OS X. So this may only be a GUI (Graphical User Interface) for something you already have but don't know how to use because it is not very user friendly and is designed for computer engineers. In Panther Apple does provide ZIP but not the rest.
FYI, If you have a previous version of Stuffit, they regularly have "specials" for $29 upgrades to the latest version of 8.02 which include all of the formats of RadicalSqueeze and a lot more with contextual menus, Magic Menu, Stuff and Mail ,Self-Extracting, BinHex, MacBinary, LHa, Bz, Stuffit and UUEncode by just renaming, encryption, etc. Anotherwords, Stuffit does it all with a better interface for another $15. This seems like a lot better value to me and includes formal support.
in my opinion, given its current feature set, at a $15 price point, this product does not represent good value, no matter how well it might work, given what else is already in the marketplace.