Anyway since it's installed, I thought I should have a play with it and note down my experiences. I'm going to start by looking at the client experience. For more information about Windows Server Essentials, have a look at this TechNet article.
Connecting to the Server
You can connect both Windows and Mac OS X clients to a Windows Server 2012 R2 Essentials server. Connecting a Windows client to Windows Server Essentials will domain join the client to the Windows domain however on Mac OS X, it does not.
To connect your client to the Windows Server Essentials server, you need to download and install the connector client which can be found on your server. Simply open up a web browser and enter in http://<SERVER>/connect. Replace <SERVER> with the IP address or host name of your server. You must be on the same subnet as your server to connect.
Follow the wizard to connect your client to Windows Server Essentials. You'll need a user account on the server in order to successfully connect. The user account you use will become the local administrator on the client you are connecting.
If you are installing the connector software on a Windows client that is not domain joined, there will be one restart to join the client to the domain. It is also possible to install the connector software on clients that are already joined to the domain.
Once the connector software is installed on your client, you'll have access to the Windows Server Essentials Launchpad. The Launchpad is just a simple app that provides access to all the services provided by Windows Server Essentials. Some of these services such as Remote Web Access will need to be configure correctly before it can be used.
Managing Windows Server Essentials
The Dashboard is where you perform all of your Windows Server Essentials administrative tasks such as adding users, removing devices, creating shared folders and managing backups. This is not accessible on the Mac OS X Launchpad though. You'll need to log on locally to the server for these situations.