I don't like SDS for multiple reasons. My biggest complaint is that it's a data structure disguised as a single naive pointer, which is actually harder to use correctly. This kind of "masquerading" pointer is conceptually a linear type, as you can't safely change its length in place and any potential change has to return the modified pointer somehow. No other type in C behaves like this, resulting in more confusion and thus more errors. And I have more counterpoints to those self-claimed advantages as well:

Counterpoint #1: You can't pass SDS strings to functions that accept `char **` (which is a common way to return a string of unknown length, and often can act as an in-out parameter as well).

Counterpoint #2: You rarely access individual "characters" (whatever this means). It is a conscious decision to whether you should iterate over bytes or Unicode scalar values or code points or grapheme clusters, and for this reason it is better to make the decision explicit even though it's C `char` in the surface level.

I have no evidence for nor against advantage #3 though.