Yes, massively influential, but was it ever used or popular?, I always think of it as sort of the poster child for the danger of "design by committee".
Sure it's ideas spawned many of today's languages, But wasn't that because at the time nobody could afford to actually implement the spec. So we ended up with a ton of "algols buts" (like algol but can actually be implemented and runs on real hardware).
Wow, The Burroughs large system had special instructions explicitly for efficient algol use. You could almost say it was algol hardware. but algol 60 not 68.
There is a large system emulator that runs in a browser, I did not get any algol written but I did have way to much fun going through the boot sequence.
ESPOL was (is?) simply a version of the standard Algol compiler that let you do 'system' sorts of things.
The Burroughs large systems architecture didn't really protect you from yourself, system security/integrity depended on only letting code from vetted compilers run (only a compiler could make a code file, and only a privileged person could make a program a compiler) - so the Algol 60 compiler made code that was safe, Espol could make code that wasn't, could do things a normal user couldn't - you kept the espol compiler somewhere safe away from the students ....
(there was a well known hole in this whole thing involving mag tapes)
As mentioned it evolved into NEWP, and you can get all the manuals from Unisys, as they keep selling it.
Given its architecture, it is sold for batch processing systems where security is paramount.
Yes, ESPOL and NEWP, being one of the first systems languages with UNSAFE code blocks, a binary that is compiled having unsafe is tainted and requires administrator configuration before being allowed to execute by the system.
One cannot just compile such code and execute it right away.
Sure it's ideas spawned many of today's languages, But wasn't that because at the time nobody could afford to actually implement the spec. So we ended up with a ton of "algols buts" (like algol but can actually be implemented and runs on real hardware).