OK, that may be a bit harsh. But the danger is that a translation that is out-of-date or badly done will turn you off the book. Many classic books whose translations are now beyond copyright are available for free. But these translations are, generally speaking, poor. To really appreciate these books, find a translation that is up-to-date and that suits your reading style.
It's often the case that there are multiple still-covered-by-copyright translations of ancient texts (and sometimes more-recent-than-ancient ones, as with e.g. almost anything Russian, or Jules Verne) that are better than anything PG has, by just about any standard of "better". Not their fault—that's just how it is. I'd definitely recommend anyone tackling these sorts of works shop for the best translation for their purposes—it can make a huge difference. Worth a trip to the library or a few dollars for a used copy, for something you'll spend hours with.