Comment by rollover

It turns away more potential customers. The DRM has helped absolutely nothing to protect against copying. The book is already out there on the net as a now "DRM-free" PDF. It's a shame that illegally downloading it is currently the only way to get the format that many customers would be happy to pay for. If I were the author I'd hurry up and quickly put a DRM-free version on a service like Leanpub.