The most impressive improvement is in the decompression, which is now up to 30 percent faster, depending on the file format you use. There's now also a password manager for regular compression jobs, though the passwords are not encrypted. Still, when extracting multiple archives you can now set WinRAR to use the same password for all of them. For more information, check out the page What's new in the latest version.
It's worth noting that as of version 4.00, WinRAR will no longer work on older Windows operating systems, including as 98, ME, and NT. The minimum requirement is now Windows 2000. On Windows 7, WinRAR will show progress of the entire operation in the taskbar.
WinRAR is available in 32-bit and 64-bit flavors. It supports the following languages: Arabic, Chinese Traditional, Croatian, Dutch, English, French, German, Hebrew, Hungarian, Macedonian, Romanian, Russian, Serbian Cyrillic, Serbian Latin, Slovak, Slovenian, Thai, and Vietnamese.
I personally have not used WinRAR for a good few years. Are you still using it? If not, what's your favorite software for extracting archives?