This is an entertaining comparison of 8 different map-reduce languages for Hadoop, including a flame-tastic take on Cascalog/Clojure: http://www.dataspora.com/2011/04/pigs-bees-and-elephants-a-c...
I laughed out loud at that.
Clojure has sophisticated state management. So much for widespread use of side effects.
Clojure has high performance data structure implementations tuned for modern hardware. So much for performance.
Clojure is compiled on the fly at the REPL and the JVM is one the fastest runtimes out there. So much for slow dev cycle.
You may not like the syntax, but boy is that Hadoop query short and sweet.