Clojure has always been slightly disappointing for me...<p>The principles behind its design are all sound and Rich Hickey deserves credit for putting in the hard thought behind it.<p>... but.... the reality seems to be of a really under performing language. The forums are consistently full of people with 'why is this slow?' to which the solution is always 'Give it more hints' or 'do it in a more Java like way'.<p>Unfortunately the Clojure stack seems not to have much mechanical sympathy (despite its best intentions). It seems the natural/idiomatic way to use Clojure results in far too much dynamic behavior to be performant.
Clojure may scale well, but its inherent bad performance (without lots of work) is a major downside.<p>I forget who said this, but it seems very appropriate to Clojurists... "Show me you can use one machine well before you get another..."