The raw basic "syntax" in terms of the parens is a bear to read (and write), but you get used to it. It may be different, but that isn't really the problem. Anyone can figure out nested parentheses and escaping. Just as someone else pointed out -- this isn't alien territory .. nested parens/brackets/whatever and literal escaping are common in complex/terse code in any of the popular languages. Possibly Haskell is different, but I find it's terse syntax of juxtaposition more inscrutable than lisp, for the most part.
The problem is that in practical terms, the lisp syntax is not just nested parens and various forms of quoting and basic function invocation. The syntax includes the positions of arguments to various standard macros and special forms. Are they are sublists or inline? what are the keywords? And most importantly, are they evaluated or not? From an academic point of few, this technically could be considered semantics of a programming language, but I think that's false -- we don't consider human sentence structure semantics. This is totally syntax. And in lisp, it's highly irregular from form to form. It's just something you have to "know" based on the form, and the lack of syntax other than parens and quotes certainly doesn't help you at all here.
Compared to something like python, it's unreadable and confusing.