When you want to learn it, I recommend the "Blue Book", aka "PostScript Language Tutorial and Cookbook" By Adobe Systems Incorporated. It's a very thin book, but a great tutorial and example reference. I enjoyed going through it, and still occasionally generate PostScript for visualizations.
Very much worth learning, if for nothing else being an extremely cool stack language. I learned it for my first job that I only had Turbo C 2.0, foxbase, and an HP4 printer with the Postscript module to do graphical reporting on a dataset.
I remember going though HP and Epson printer manuals, writing down their control escape codes into a xBase table so that our Clipper application could talk to the printers and do the respective formatiing.
Having access to a PS printer would have been a much more positive experience.
I used to hand-code Postscript files back when the Apple LaserWriter was launched. I had a little kaleidoscope-like thing that did patterns for Xmas decorations, and once I did a text-to-workflow routine to print out diagrams. It's all gone now (I did part of it on a VAX and part on an SE/30), but it was lots of fun at the time.
When I was actively play with Sudoku programs, I wrote a bit of code that generated sudoku images in svg, (e)ps and and a few other formats. It was a bit fiddly, but not really complicated.
