Microsoft's plentiful work in 2012 was spent towards making Hyper-V more competitive with features of other virtual machine and cloud services vendors, but also in out-featuring its competition in management and enterprise-focused control-plane capabilities.
You don't have to deploy all of the options to get just traditional file-and-print, Active Directory Controls, and MS Exchange going -- the most popular basic combination.
What Microsoft has added is the ability to get to those extra features rapidly and with rational procedures for civilians, or modifiable-then-deployable payloads for larger organizations that must distribute customized server payloads. And it's all 64-bit, even 32-bit in-place upgrades aren't possible. Microsoft's website offers extensive detail on upgrade paths from current versions of Windows 2008.
There are two forms of the Windows Server 2012 -- "Standard" and "Data Center"; both can be optionally run over Hyper-V. Two user-limited versions, Windows 2012 Essentials (25 users, 50 devices, one server) and Windows Server 2012 Foundation (up to 15 users, but without Essentials application features that are much like Windows 2008 Small Business Server/SBS) are available but aren't covered in this review.
Each Windows Standard/Server license covers just two physical processors, which we found comparatively limiting, although somewhat inline with hypervisor competitor VMware -- where you'll pay for the hypervisor license and in addition, the Windows license. Standard edition allows two VMs; licenses can be stacked up to eight VMs for two licenses on the same server. Data Center licenses are essentially unlimited, subject to the two physical processor rule. CAL (Client Access Licenses) are roughly the same as before, and Remote Access (VDI) sessions also require additional-cost licensing support in many cases.
We could also choose to install in a GUI- or GUI-less version, "Server Core". Windows 2012 as an operating system on media, can be mounted, added-to, or modified within constraints for either the full-installation, or a sparse one, prior to installation. Although we couldn't find directions regarding putting the operating system on a diet, we know that the payload can be reduced dramatically. A lighter payload makes it non-standard for purposes of later adding software, but for organizations seeking sparse instances to virtualize -- it can be done.