Top 10 Features in Windows Server 2012

1) Scale and performance
...Hyper-V in Windows Server 2012 greatly expands support for host processors and memory. New features include support for as many as 64 virtual processors and 1 terabyte of memory for Hyper-V guests, a new VHDX virtual hard disk format with larger disk capacity of up to 64 terabytes, and additional resiliency.
These features help ensure that the virtualization infrastructure can support the configuration of large, high-performance virtual machines to support workloads that might need to scale up significantly. Significant additional improvements have been made across the board, with Hyper-V now supporting increased cluster sizes, a significantly higher number of active virtual machines per host, and additionally, more advanced performance features such as in-guest Non-Uniform Memory Access (NUMA). This capability helps ensure that customers can experience the highest levels of scalability, performance, and density for their business-critical workloads.

2) Share-nothing live migration
 ... is a mixture of SMB3 live migration & storage live migration. Basically you move an image between hosts with just an Ethernet cable attached.

3) Hyper-V Network Virtualization
...Isolating virtual machines of different departments or customers can be a challenge on a shared network. When these departments or customers need to isolate networks of virtual machines, the challenge increases. Traditionally, virtual local area networks (VLANs) are used to isolate networks, but VLANs become very complex to manage on a large scale. Hyper V Network Virtualization helps solve this problem. With this feature, you can isolate network traffic from different business units or customers on a shared infrastructure without using VLANs. Hyper V Network Virtualization also lets you move virtual machines as needed within your virtual infrastructure, while preserving their virtual network assignments. Finally, you can even use Hyper V Network Virtualization to transparently integrate these private networks into a pre-existing infrastructure on another site!
 
4) Hyper-V Replica

...Provides a storage-agnostic and workload-agnostic solution that replicates efficiently, periodically, and asynchronously over networks based on Internet Protocol, typically to a remote site. Hyper-V Replica also allows an administrator to more easily test the replica virtual machine without disrupting the ongoing replication. If a disaster occurs at the primary site, administrators can quickly restore their business operations by bringing up the replicated virtual machine at the replica site. Hyper V Replica provides a virtual machine–level, affordable, reliable, and manageable replication solution that is tightly integrated with Hyper V Manager and the failover clustering feature in Windows Server 2012.
 
 
5) Tired of expensive SANs? Well 'might' be the answerSMB3
 
...Windows Server 2012 introduces new File and Storage Services features that let you store server application data on file shares, to take advantage of the new Server Message Block 3 (SMB3) protocol and benefit from low-cost, "commodity” hardware. A variety of performance enhancements and availability improvements come together to make file share storage a great low-cost choice for critical workloads such as Hyper-V and Microsoft SQL Server. File and Storage Services now can endure a variety of failures transparently—resulting in minimal interruption in service to the users (or servers) that depend on them for storage. These File Server features allow you to more easily create and manage an optimally available data storage foundation for critical application services such as Microsoft SQL Server and Hyper-V. An array of new server message block protocol enhancements and capabilities such as transparent failover, SMB Direct, and SMB Multichannel give you benefits and performance that are similar to much more expensive storage area networks (SANs).
 
6) Windows PowerShell 3.0

...Powershell command-line interface provides a comprehensive management platform for all aspects of the datacenter: Servers, network, and storage. In this version of Windows PowerShell, sessions to remote servers are resilient and can withstand various types of interruptions.
 
7) Hybrid applications
 
...The following capabilities in Windows Server 2012 help provide the flexibility to build and deploy hybrid applications on-premises and in the cloud:
• Programming symmetry across premises and the cloud -Provides the ability to use the same development model across Windows Server 2012 and Windows Azure.
• Common development tools -Microsoft Visual Studio and Microsoft Team Foundation Server provide a rich Development experience and offer to Microsoft .NET developers a more complete environment to build cloud and on-premises applications.
• Connectivity for hybrid scenarios enables integration of applications across Windows Server 2012 and Windows Azure though different levels of connectivity:
           -Application-layer connectivity and messaging through Windows Azure Service Bus.
           -Machine-to-machine connectivity across cloud and premises through Windows Azure Connect.
• Machine-to-machine connectivity across cloud and premises through Windows Azure Connect.
• Virtual machine portability across premises and cloud. Offers the options through Microsoft System Center or the services portal to provision, manage, and move virtual machine images between Windows Server 2012 and Windows Azure.

8) Multitenantcy
...Network virtualization decouples server configuration from network configuration to provide a virtual dedicated network to each tenant. This allows seamless migration of workloads, while continuing to provide security isolation between tenants. Partners have the opportunity.

9) VDI Scenario
...Growing adoption of VDI desktops in the enterprise requires tools that can help streamline deployment and management tasks for IT administrators. Windows Server 2012 provides a number of enhanced features that help to simplify and expedite these tasks, including:
• Simpler wizard-based setup procedures for Remote Desktop Services deployments.
• A unified management console for virtual desktops and session-based desktops and applications.
• Simplified creation, assignment,and patch management of pooled and personal virtual desktops.
• VDI in Windows Server 2012 Remote Desktop Services, which delivers a consistently rich experience to users
on different devices, in various locations, and over changing network
conditions.

Some of the key enhanced features in Windows Server 2012 supporting this experience include:

- RemoteFX Adaptive Graphics: Provides improved graphics processing that enables smooth delivery of virtual desktop and RemoteApp programs. It also provides an enhanced Windows Aero and 3-D experience across  various networks—including those with limited bandwidth and high latency. 

- RemoteFX for WAN: Delivers a number of technical improvements that enhance the user experience when connecting over wide area networks. This is especially important for people connecting from dispersed locations such as branch offices, homes, or hotels with low-bandwidth connections.

- RemoteFX Multitouch: Lets users of new kinds of touch-enabled and gesture-enabled applications take
advantage of these solutions in remote-desktop environments.
 
10) DAC - Dynamic Access Control
...Further improvements to DAC has be added to Windows Server 2012. Previously, file security was handled at the file and folder levels. IT professionals had little control over the way security was handled by users day to day. Now, by using Dynamic Access Control, you can restrict access to sensitive files—regardless of user actions—by establishing and enforcing file security policy at the domain level to enforce it across all Windows Server 2012 file servers. For instance, if a development engineer accidentally posts confidential files to a publicly shared folder, those files can still be protected from access by unauthorized users. In addition, security auditing is now more powerful than ever, and audit tools make it easier to prove compliance with regulatory standards, such as the requirement that access to health and biomedical information is guarded correctly and monitored regularly. Audit logs can also be collected with SCOM 2012.