Digital Rights Management (DRM), in the long run, is bad for everyone. Even in the short term, DRM is bad for most people with a select few benefiting from its use. Personally I try to avoid DRM at all costs although it is impossible to do so these days. DRM can do many things but, for all practical purposes, DRM is simply a copy protection mechanism.
Most people are clueless when it comes to DRM until it comes back to bite them. Take Amazon's Kindle for example. Amazon sold a book that it had to later recall. It did so using the wireless connection in the Kindle and deleted all occurances on Kindles in the wild where users had bought the book. They were nice enough to give everyone a refund but many found this to be more than just annoying. This and other mechanisms can be used to implement all sorts of onerous actions.
Just take a look at the wonderful contracts that are associated with software and service. Many have a clause that lets one party change the contract at will. Consider someone adding a recall option to the contract that can be arbitrarily executed. Better yet, the contract text could be controlled by DRM and deleted.
What is really bad is the impact of these actions could have over time. Imagine needing instructions on your Kindle for a piece of hardware that is currently running but the instructions have been recalled. Personally, I don't like things disappering on my. I lose enough stuff on my own.
Luckily many of the ebooks I want come from a publisher called Baen that does not use DRM at all. Baen publishes sci-fi and fantasy books so it is not for everyone but it is an approach that I would hope move publishers would follow.
I'll probably do another rant or two on DRM in the future because there are so many issues to consider.