Microsoft have just released Azure Stack Update 1.1811.0.101, and for me, it is one I am looking forward to implementing now that I have read the release notes on the new capabilities. For some, the headline feature is the introduction of Extension Host, which simplifies access to the portals and management endpoints over SSL (it acts as a reverse proxy). This has been known about for some months, as Microsoft have been warning operators of additional certificate requirements and to be ready for it: https://docs.microsoft.com/en-us/azure/azure-stack/azure-stack-extension-host-prepare. This is good, as it means less firewall rules are required and I'm all for simplification, but not the most exciting introduction for me - that's the support for service principals using client secrets.
I've been working with Azure Stack with AD FS as the identity provider for many months and previously the only way to provision Service Principals (for use by automation or applications) was to use X509 certs for authentication. Setting up the certs is pretty cumbersome , as they have to be generated, imported to systems that you want to run the automation on, grab the thumbprint, generate PEM files with the private key for use with Azure CLI. For me, too many areas where stuff might not work (e.g., the certificate may not be present in the local computer store where the automation is running and throw an error.)
Using X509 certs to authenticate worked for a some scenarios, but not for others. For instance, a number of third party solutions//tools (and first party!) couldn't be used, as they were written to be compatible with Azure AD Service Principals (which primarily uses secrets). One example is the TerraForm provider; prior to this update, it could only be used for Azure AD implementations, but in theory it's now open to AD FS as well. What this release also opens up is the possibility of deploying the Kubernetes ARM template that is currently in preview. The template requires a Service Principal ClientID and Client Secret, so blocked deployment to disconnected systems previously.
I haven't had the chance to apply the update yet, but I will do it ASAP and look forward to testing whether client secrets for ADFS works as I expect.