[ssivark]

Yeah, I've used it quite a bit and would consider myself an intermediate user. It's a very pleasant language to use (everything is an S-expression underneath, and computation happens via "term rewriting") once you get used to it, but it's declarative nature of programming makes it similar to eg. Haskell/Lisp and quite different from eg. Python/Matlab. It's basically unmatched for symbolic manipulation and algebra, so it's very popular among theoretical physicists (that's how I encountered it).

My only gripe with it is that it's not open/free (as in freedom), so the platform is limited by Wolfram's imagination (and different pieces don't always compose nicely, unlike say, in Julia) and I don't want to become dependent on a computing platform whose future is murky (bus factor of one, at least from what Wolfram takes credit for). Otherwise, I wouldn't mind paying for a personal use license and using it more.