Python: Indentation is used to specify block structures rather than brackets or braces. Also, heavy use of colons and underscores and module/variable name collision.

LabVIEW: The GUI programming approach can make anything beyond the simplest of tasks extremely complex.

JavaScript: Case sensitivity, different implementations across browsers, lack of debugging capabilities (though Firebug solves that) and odd inheritance rules.

COBOL: Extremely verbose syntax (it was intended to be readable by non-programmers), incompatibility between versions, and, prior to COBOL 2002, lack of support for object oriented-programming, functions and pointers.

C++: Too big of a feature set, manual memory management, slow compilation speed and the fact that it allows programmers to switch between object oriented and procedural code in the same program.

Java: The syntax is too verbose, it’s slow, it’s not easy to pass functions, the API’s are over-engineered and lots of other languages can do what it does, but more efficiently.

Perl: The main criticism against Perl, consistently, is that there too many ways to do things. So many, in fact, that it’s essentially a write-only language, meaning Perl code becomes impossible to read (and, ultimately, maintain).