ArsTechnica posted a review on Windows Server 2012 R2 Preview

Now Microsoft has unveiled the preview of Windows Server 2012 R2. It's not just a "service pack" of bug fixes for last September's release—this is a full update with a raft of further improvements targeted at further knocking down the walls between on-premises servers and private and public clouds. Some of those changes fine-tune the balance between simplicity of management and the enterprise power Microsoft was going for. They continue to enhance the server platform's suitability both as a component of a cloud-computing environment and as an on-ramp to cloud services for small and mid-sized organizations.

Microsoft is also previewing updates to its system management platform System Center 2012 R2 and to Windows Server 2012 Essentials, the "easy deploy" successor to Microsoft's Windows Small Business Server. Among other things, System Center 2012 R2 and Windows Server 2012 together improve Microsoft's support for Linux virtual hosts within a Microsoft-managed environment. And the new version of Server Essentials has bigger ambitions than just the server under your desk—it's been beefed up to appeal to mid-sized businesses and optimized further for deployment in the cloud. Now service providers can offer hosted Windows domains to their customers and give them simple-to-use administrative tools that can be remotely accessed.

  Windows Server 2012 R2 Preview: Your cloud on-ramp is under construction