Some of the problem with regexes isn't the language itself but what people try to use them for. They will write lines and lines of regexes when what they really want is a fairly simple parser.
Regexes are great for simple to moderately complicated substring matching and data extraction. But at some point of complexity you have just got to whip out the compiler-compiler and write a real parser. I think a lot of people don't realize that regexes are primarily for matching, not for doing parsing.
