I have been testing out OS4 for quite sometime, primarily their XFCE spins with BeeOS theme (in 13.6 release, of course, they changed it for better!). Mostly, they bring out user-friendly spins with all available multimedia codecs and plugins to make OS4 a good option for Linux novices as well as experienced users. For this review, I take up the latest update of OS4 KDE spin. OS4 OpenLinux 13