Comment by zozbot234

It's quite secure against casual attacks, but a proprietary mobile platform has inherent issues wrt. withstanding even mildly sophisticated attackers, including mercenary spyware services. You still have a huge attack surface from all sorts of proprietary firmware blobs and hardware IP blocks that are running directly on the SoC. It's not clear that it's really worth even trying to secure it as opposed to just treating it like an untrusted toy.