Kindle DRM doesn't annoy me at all. I'm not annoyed by just the existence of some technology, I'm annoyed if this technology hurts my ability to do what I want to do. I do want to read books on iPad, iPhone, Mac, PC and Kindle. I'm able to. If I wanted to steal books I could have been annoyed, but I don't want to.
1984 demonstrated that your ability depends on the continued goodwill and competence of Amazon, who reserved for themselves the power to steal any of your Kindle store purchases.
PDF is an open standard, the Kindle format is not.