Well is that really true? They've bundled loads of features into the format, the other readers might be safer but only because they don't support those features

Well is that really true? They've bundled loads of features into the format, the other readers might be safer but only because they don't support those features and they will try to add them at some point. Also PDF is based on postscript which is programming language. It's sufficiently complex that's is never going to be very secure, and after all the main problem with Office documents was Macros.