A determined hacker can break DRM. It is better in terms of security, but the tools available to crack it are relatively easy to come by.
As with most protection schemes, it ends up being more of a nuisance for legitimate users than a deterrent to thieves.
And it doesn't even take too determined of a hacker. Breaking DRM is apparently not that hard. And, if you were so inclined, if you can see text on a page, which happens whether there is DRM or not, you could take screenshots and use OCR or any other number of methods to copy a book.
Reflowable formats are almost certainly more popular, but I have noticed that, when given a choice, some people will opt for PDF. Also, BookFunnel has always offered that as a choice, which I doubt they would if in fact no one wanted it.
Personally, I've always preferred PDF. I don't need special software to read it. That is, on the Mac, the built-in Preview app will open PDFs. And, Adobe Acrobat Reader is a free download anyway. And there are plenty of other options software-wise for reading PDFs. If I am so inclined, I can also print it and read a hard copy. Yes, sometimes PDFs can be locked to prevent printing but, sometimes, even if you're not a hacker, there are ways to get around that.
BUT, the "word" was that no one wanted PDFs. Or that PDFs were bad because it made your books easier to steal. Those were the mantras at That Place That Shall Not Be Named. And, despite that, I've downloaded and read PDF books and I know others that do the same. I know one person that will read PDFs on her phone, even if the PDFs aren't specifically formatted for mobile devices. Outside of Kindle author circles, PDF eBooks have been quite common. I used to do some of mine where they were formatted to leave space for a 3-hole punch so people could print and keep them in a 3-ring binder if they wanted.
So, it's kind of like Amazon is catching up with what the rest of the world has been doing since 1995.
