[rbanffy]

It really depends on your use.

If you already paid for your Windows license, not that much. The way it ties into the OS is a bit concerning to me but, apart from that, it's OK.

I think the question can be formulated in a different way: what's RIGHT with using IIS? What does IIS offer you that other web servers don't? Easy AD integration is the one thing that crosses my mind, and I can't think of anything else besides "it's already there".

If you plan on scaling out, however, licensing costs will grow quickly. If you run .NET Core apps, the built-in HTTP server is very fast and runs on Linux as well. Same story with Spring apps - using Netty/Jetty or even Tomcat is easy and makes your app very self-contained.

I think the big nope for me is that it is from the "Pets" era, before servers were "cattle", which was compounded by containerization and tools like Kubernetes and OpenShift. IIS just doesn't look like it fits into that new model.