It runs also on Linux, Mac OS X and Free BSD platforms.
WinRar supports RAR and ZIP files and can unpack 7Z, ACE, ARJ, BZ2, CAB, GZ, ISO, JAR, LZH, TAR, UUE and Z formats. It has its own compression algorithm that rise compression ratio up to 50 %. It supports SFX so you can create self-extracting archives, Unicode in file names, and some backup facilities such as repairing a broken archive.
The interface is user-friendly, is easy to use and highly customizable for both versions. The graphical user interface supports drag-and-drop and integrates a wizard interface that allows novice users to do basic and simple compression and decompression operations. You can download plenty themes and skins from the producer's site to personalize the interface.
WinRar is a solid full-featured tool for managing archive files and even though is not free, the 40 days trial version lacks none of the mentioned features, so I recommend you to use it and not lose your time with serials, cracks or key-generators.