They're more secure (albeit in many wsys security through obscurity) than private, although the privacy aspect is probably among the best you can get by default as far as I can tell. On the other hand, if you're willing to do some relatively simple steps and buy specific hardware, you can achieve better privacy and security on both mobile (graphene) and desktop (qubes) devices.
I personally dislike them for building unrepareable crap, tho.
Well, duh. All governments are cancer