Printer Sharing, GPO, scripting, support for windows apps, network flexibility (aka cannot change IP of the NDSC containter), partition and volume management
Licensing, mail server, app server, chat server, stability, lack of extra tools (most of tools are integrated), hardware request
Too many things missing thing for “kill” Windows in a well integrated environment.
Also, for quality conscious-enviroment a lot of reports are missing. As perspective of not-tech people, this is not even RedHat (which is a certified software). It’s a mangled CentOS.
Therefore, keep trying. Maybe more user-based issues could route NethServer into a real Windows Server alternative…
If budget is a nice hit for prefere Nethserver, sometimes if a company is already using and paying Windows could try to be a bit wider for searching licensing partners.