I happened to use all three of the Sun Labs languages the article mentions, around that time. My university had a relationship with Sun, so I got to play with Self, and I added autoindent to the morphs world trait editors. Where I was working in parallel, I was responsible for the Tcl-based extension language for a commercial CAD-like system. I also got an advance look at what became Java, and later I wrote some of the first Java application code outside of Sun, plus some fancier GUI widgets.
All three languages were innovative, but I'd say Self had more innovations. Students of programming languages would do well to take a look at Self, even though things like JIT, prototype object models, and direct-manipulation graphics worlds are now used elsewhere.