I really like how most of the non-sexp syntax is optional in CL. Anyways, I'm also a bit ambivalent about the merits of [] vs. #(): I like how the latter syntax is more "standard", since the # dispatching macro character is used for a bunch of things. E.g. multidimensional arrays #2a() #3a() complex numbers #c(1 2) character literals #\space, pathnames #p"/foo/bar" etc.: it adds to the uniformity of the syntax, ime.