I program in K, a close relative, and I have done some tinkering with APL. The symbols actually don't take long to memorize- perhaps a few days of practice. It's a bit like learning to read prose. At first you have to sound out words letter by letter, but eventually you're able to "see" words and phrases built out of common patterns of symbols. I see ,/f' and think flatmap, ~~': and think heads of uniform runs, {x@<x} and think sort up, etc.
A dense expression can still take a while to puzzle out sometimes, but certainly no longer than the equivalent logic spelled out in a more verbose language across many lines.
I've looked at some of the ascii APL relatives, and my impression was that they are probably great for working with numbers, but seem like they'd be bad for working with text and other things. Am I missing something here?
K relaxes the traditional APL constraints on "rectangular data", which makes it comparatively quite good at dealing with text manipulation. I frequently use K for working with text and it works nicely. Anything you can represent as a list structure can have all the traditional APL-ish tools brought to bear on it.
As for "other things", here are a few K sketches I've written recently:
A dense expression can still take a while to puzzle out sometimes, but certainly no longer than the equivalent logic spelled out in a more verbose language across many lines.