The live IDE thing - which isn't a gimmick at all, in my opinion - really is the only thing left that sets Smalltalk apart in 2020. Besides that, it's a very simple, dynamic, single-inheritance class-based pervasively object-oriented programming language that doesn't do anything especially interesting these days. Of course, while it was being developed in the 70s, all that was pretty revolutionary!
The closest popular language to it today is probably Ruby, which was directly inspired by it and is similarly dynamic, single-inheritance, class-based, and pervasively object-oriented.
I would say something like LispWorks, Factor or even JavaScript with the browser console do a better job at this.
I have given Smalltalk plenty of tries, and always ended giving up due to the lack of polish prevalent on all current implementations:
Pharo looks blurry on my Macbook and is crashing all the time.
Squeak is a bit more stable but feels and runs like a toy.
Cincom is a tad better and has a pretty nice UI designer that is best in class (I would be embarrassed to give a client the ugly non native user interfaces that I see people building in Pharo) but I had the community version (which is not even the latest version) also crash on me a few times and you cannot test it on macOS Catalina / Big Sur.
The closest popular language to it today is probably Ruby, which was directly inspired by it and is similarly dynamic, single-inheritance, class-based, and pervasively object-oriented.