Think about what immutability means. It means that there's no assignment statement. If there's no assignment statement, there can't be any side effects. If there are no side effects, you can't race conditions or concurrent update problems. You can't have resource leaks. You can't have order dependencies.
Does Clojure guarantee all these things? Not entirely; because Clojure allows you to invoke the java stack, which is decidedly not immutable; and because clojure provides mechanisms for changing state; albeit with significant discipline imposed.
The end result is that clojure is _much_ safer to use in complex and multi-threaded systems, and is likely much, _much_ safer in extreme multi-core applications.
Does Clojure guarantee all these things? Not entirely; because Clojure allows you to invoke the java stack, which is decidedly not immutable; and because clojure provides mechanisms for changing state; albeit with significant discipline imposed.
The end result is that clojure is _much_ safer to use in complex and multi-threaded systems, and is likely much, _much_ safer in extreme multi-core applications.