I like the idea that notation is a tool of thought, but I think that J (and APL) are actually rather crappy notations. I FAR prefer matlab for matrix work, as it is closer to actual math than any other language I know. For logic ish programming, Prolog or AMPL or SQL (I like SQL, even though people hate on it all the time). But, in my humble, J and APL are interesting historically, but rather crappy in comparison to…
Have you ever used J or APL seriously? If yes, what do you find so "crappy" about the notations? If no, please keep your uninformed opinion to yourself, you have no idea what you are talking about.
And my somewhat informed opinion is that J sucks ass. To start with, input/ output suck and it's hard to read and maintain -- it is the least pragmatic language I know. But what I really hate about it is the community -- full of true believers who think it's a cosmic language and "mathematical", even though you can't prove theorems in J (that's what would make it mathematical, duh), who babble about how they can calculate pi to 1000 digits in only 4 characters, as if that is remotely useful or profound (neither)