They allow you to record scripts in your favorite .NET language and then you can modify them and add stuff to your liking. So far, all I have to do is port 2 classes I wrote in Python using TestComplete to automate install/repair/test/stress/uninstall our products.
you need VS 2015 or 2017 Enterprise. Unit Test projects also rule, but these are so convenient with the recorder and all. FAST development.
If you are a professional Windows apps developer, you really need MSDN subscription. Make your life simpler.