Ranked in these QuestionsQuestion Ranking
Pro Batteries included
Base system contains basic developer tools, including compiler, debugger and system utilities.
Pro Powerful ports collection
Ports provide a wide collection of software which are easy to build, install and modify. They contain recipes and patches to build various software, so you can simply run "make && make install" to build and install the software. You may also keep local patches and it would be picked up automatically. It also allows you to use the latest software even if you are not using the latest version of the operating system.
Pro Jails mechanism
Jails allow for partitioning a system into several independent "mini-systems", a feature not found in many of the popular OS choices.
Pro Stable updates
Con Inferior driver support for workstations
Lack of drivers for some modern personal devices.