It is a very cool operating system. I had the pleasure of configuring it (in it’s ibm z/VM form) from scratch a few years ago. However due to company politics it only ran for 2 years. If you are based anywhere in the US you could probably make a career out of it. If you are in Europe I don’t know if it is a wise choice. Not much z/VM there. If you now own a modern mainframe and want to run Linux workload for example I think you are better of using kvm. However if you need to run z/OS virtualised your only option is still z/VM