Earlier quoted context omitted.
It uses raw lists as the data structure for everything (including code) and has enormous math/sci and presentation infrastructure. Every part of the system can easily talk to any other part of the system. Because of this you can just throw things together and get great results, where in other systems you might need to use external libraries or otherwise have to deal with high-ceremony architecture (I'm looking at you…
You can only "easily" "throw together" things if you have any clue about a) where to find things, and b) how you can make them fit together. The problem with Mathematica is that neither of these is easy. I mean, look at their literal Hello World example: GeoGraphics[Text[Style["Hello!", 150]], GeoRange -> World] In any other language, if I wanted to write some text on a graphic, I would find a routine to load an imag…
img = Import["c:/blah/blah.jpg"];
ImageCompose[img, Rasterize["HELLO"]]
You're right that it might not be obvious what to search for, but in this case you would search for "image" or "importing" or "overlaying" and you'd figure it out.
Mathematica uses a 'compositional' model like some other functional languages, as opposed to a 'memory' model like system languages, so that could take some getting used to if your background is system languages.