Why should I learn and use Solaris?

Solaris is very good stable operating system. Advantages of Solaris

1. File system - ZFS file system most amazing file system in the world.
2. Operating System stability and will not get any hung issues
3. RBAC is amazing feature for user base access restriction ,etc

If you are in unix world than you can't ignore solaris.even if you are using linux flavors at one time of your carrier you may think of learning  / using solaris because of your desire to learn it or job requirement. any project requirement. but what ever the reason unix system administrator must have a go on solaris along with linux and aix. In my personal opinion as i find many jobs where they asked for mix of enviroments in unix sys administration.