That's very accurate. So dead simple that as soon as you want to manipulate something else than primitive values and functions from JS, you hit a dead end. How do you read a field from a JS object? How do you call a JS method? For all these things, you have to write "bridge" JS code that exposes JS libraries in a way that PureScript is happy with.
It's also striking to me that the documentation of PureScript FFI [1] has to teach you what the output of the compiler will be so that you can use the FFI. Am I really supposed to know about those `$`s? What if the compiler improves and changes its internals?
I'm sorry if my comment is perceived as a rant, but I can never understand how people can call PureScript's FFI good. Compare it to interoperability in TypeScript, ClojureScript, or Scala.js, and it is way behind!