>> The parenthesis do require that you have at least a moderately capable editor to navigate them effectively.

I disagree, with a caveat--writing code using a terrible editor requires knowledge of the indentation rules for the language, regardless of whether that language is a lisp, Perl, Ruby, etc.

However (the caveat), although the indentation rules for Perl, C, Python are relatively simple (indent after a '{' or ':', line up arguments), each function/macro in a lisp can have different indenting rules (e.g. in CL compare `let' to `multiple-value-bind' to functions, to lists, to the various `with-*' macros, etc).

Once you know the library for a specific implementation, the indentation rules become more obvious; at this point, using (e.g.) Notepad isn't particularly terrible (until that knowledge is acquired, though, yikes).