I wouldn't call them useless, but I guess I'm used to C++, or worse, just a hex stack dump (yay, game consoles). Clojure mangles names somewhat to make them Java-compatible; you can easily do the reverse translation in your head. Still, this could be automated rather easily.
As far as I remember clojure just spit out "This is not a function" or something like that, without any indication where the error occured.
There is a trace macro but it doesn't provide complete traces without explicitly adding every function you want to trace, which becomes tricky very soon. Manual tracing with printf()s like in non-functional languages isn't built-in either. There are half-baked macros for this on blogs if you google hard enough, but that is not the kind of thing that leaves a solid impression of a language.
Maybe I was just working in a non-clojuresque way.
I agree its a problem. I use the repl a lot and bild up the functions and debug with prints witch is ok because you can print anything (not like in VB). I know that they are working on it so I hope it will get better.