Perl is too loose for a first language. A first language should be something like Pascal (designed as a teaching language), which is strongly typed and doesn't allow much flexibility. A first language should be something that teaches good practices.

Later, a student should be taught when those practices are unwarranted. But, those situations are very rare and usually involve very advanced topics. In that situation, Perl makes an excellent second language. One cannot appreciate the flexibility Perl offers without having had to do it the "hard way" first.

This is how I learned programming. 10 years later, I still appreciate Perl for what it does for me, and try to do the same with what I develop.