I had it in an engineering inner sanctum of Apple. had used it since it came out in 1988 on campus in Illinois, and folks in Apple definitely knew it. Not sure who all was doing what with it.
SJ recommended some of the UI bits of the notebook. Particularly the separators between cells.
Wolfram had come up with some normal techie names "computron", "math-o-matic" or whatever. SJ said No those suck, use something simple like Mathematica.