VMware vSphere Review
Old, almost dead, but still great software to play with, but not for your production environment
Unlike VMware workstation where we have to log in to desktop to run VM(s), with VMware Server we can run VM on the background. It also have a web based management interface so you don't have to install a software on your desktop to manage VMware server. It’s still quite useful virtualization software that you can use for free if you want to spend extra mile patching some files before you can compile support for your kernel.
Room for Improvement:
VMware server already reaches its end of support on June 30, 2011. Since it’s not supported anymore, and new support for newer OS, if you use a new Linux distro, you have to patch some files before you can compile support for you running kernel.VMware itself suggest its users to move to VMware Player if you only need to run small number of VMs on your desktop, or VMware vSphere Hypervisor if you want to run on dedicated machine.
Not the best choice if you want to start learning virtualization. You better choose VMware Player, or VirtualBox if you want to run virtualization software on your desktop or VMware vSphere Hypervisor and XenServer Free edition if you want a free virtualization software on a dedicated machine.