The #1 reason customers email (and tweet and in-message) the Azure AD team is to ask them to add support for Azure Resource Manager based virtual networks to Azure AD Domain Services.
So we're excited to announce the public preview of Azure AD Domain Services support for virtual networks created using the Azure Resource Manager deployment model. You can now create new managed AD domains in virtual networks that were provisioned using Azure Resource Manager. This public preview release makes deployment of Azure AD Domain Services much easier for you!
Read all about it in the Enterprise Mobility & Security blog.