The book was published in 2001, so as far as technology books go, it's very old. However, it's held up well, and gives excellent advice on how to use Perl to process data. As long as it's used with a more modern Perl book, (e.g., Modern Perl or Perl Best Practices) I have no problem recommending it.
Day-to-day, in the trenches, this is the book that has influenced my own coding more than any other. Lucid and practical; every page brims with proven advice.