pdfs suck as game books. At best, you can preview a book with an illege pdf before ordering it online, but pdfs suck as game books and I can't imagine using one.
Even if you steal a book by getting an illegal pdf, you are in practice still going to have to pay for making an inferior print out of the pdf and binding it in something before its really going to be useful for thumbing through, serious reading, or anything else.
For that matter, this is the reason I don't buy legal pdf's. Some of the material out there looks really great, but as a media for a rule book, digital copies just suck.
If you are planning on playing
4e, I can't imagine why you wouldn't want the rule books. I can't imagine from any perspective, ethical, practical, or anything else why you'd be happy with a stolen copy.
And yet another word from our sponsors
