Well, it is perhaps the most complete suit of web compressions out there. 7zip might beat it at compression at times, but there is no interface for 7zip that can come close to WinRar. Oh, now there is! WinRar added support for 7zip in this latest version in addition to these updates:

“Fastest” (-m1) RAR compression method has been modified to provide much higher compression speed and lower ratio. It may be useful for tasks requiring the high speed like regular backups.

WinRAR is able to decompress archives created by Unix ‘compress’ tool (.Z files). Like GZIP and BZIP2 archives, WinRAR opens tar.Z and .taz files in one-step, so users do not need to unpack .tar manually.

WinRAR is able to decompress archives created by 7-Zip (.7z files). “Find” command is not supported for this archive type.

Solid update…

Download: WinRAR v3.40 | Changelog