Just happened to a friend, she can't install the update she had downloaded.
Problem is, if you were quick on the draw and updated as soon as it came out, there's no ipsw for the iPhone 6/+ on the dev center. Though the solution is to restore to last known good, LKG is not available through the usual channels.
My heart goes out to those unknown folks at Apple who are now having a really bad day. I doubt we'll get it, but I'd love to read a post-mortem of this event. I suspect it'd be educational, as I have a hard time imagining how an org like Apple could ship a release this obviously broken.
Caveat: I have not tested these myself, nor has anyone on my team. We are holding off until we deem it necessary to get the devices working again (an enthusiastic tester who was quick on the draw this morning managed to hose our only two iPhone 6 devices.)
I wonder what I do with my now-eternally-updating iPhone.