Clojure uses {} for maps, #{} for sets, and [] for vectors, and vectors are used in function definitions, let statements, etc. This slight decrease in regularity makes a lot of functionality more visible. For example:

SBCL:

(defun f (x y) (let ((z (gethash x :a))) (+ z y))

Clojure

(defn f [x y] (let [z (get x :a)] (+ x y)))

Having syntax for maps is a huge win. Like ML's pattern matching, it's one of those things that changes your coding style entirely for the better, in a way that you wouldn't predict just by looking at the feature.

The only think I miss from CL when I work in Clojure is keyword arguments to functions. There, the Clojure way is a bit worse:

(defun f (x &key y z) (list x y z)) (f 2 :z 3) => (2 nil 3)

(defn f [x {y :y z :z}] (list x y z)) (f 2 {:z 3}) => (2 nil 3)