The language is quite elegant and has some really good concepts, but it lacks many of the things that make programming an enjoyable activity for serious work in the modern day. While the language is incredibly dynamic, it works like a low-level language for everything but displaying 2D vector graphics (where it is actually good). If you want to concatenate two strings, you'll have to implement that function.

IMHO, the real problem with PostScript is that the language has not evolved at all for like 25 years. That's a lot of time during which it could have transformed into something truly spectacular.