I investigated it a while ago when looking for a tool to lighten CPU/RAM requirements for virtualization on Linux. It seems legit. But remember, Windows was never meant to have some of these things done--you'll have to be careful with what you choose to do and have enough understanding to fix things if you get yourself in a rut.
Remember, tools like NTlite, WinUtil, BCUninstaller, debloat scripts, registry nuking guides, etc, are not intended by Microsoft to be used by consumers. Some (many?) may not even be safe. It's good that you are being careful and checking. There are some enterprise-level tools that allow enterprises a much more granular level of control, but none of it is meant for regular users--especially those who are uncomfortable with computers.
