I used (and still use) Window Maker for almost a decade before learning what NeXTSTEP actually was (i heard about the name occasionally but never looked into it), then for several years before even trying one. I remember having a heavy sense of uncanny valley because the thing in front of me looked almost exactly like what i was using for years but it behaved in very odd ways (and lacked most of the window management features i came to expect) :-P. It made me realize what people who were used to Mac OS X felt when they tried the various Aqua GNOME/KDE themes that were popular on Linux desktops some years ago.
Due to similar realisation, my main working devices became Window 7 with Virtual Box/VMWare Worstation, nowadays WSL.