iPhone 6 Crashing to Apple Logo
I've been getting this periodically as well. Didn't get it with the betas, but with the final release. It also seems to be related to home screen swiping for me. If I navigate the home screen after I've had a memory-intensive app open or I'm doing something in the background like downloading app updates, and I swipe between home screens two fast, I get this. In fact, if I trigger a series of updates and start playing around swiping between home screens, I can usually make it happen. It's a Springboard crash, so the phone is not technically rebooting, but the process that handles the home screens is crashing, and it also has the effect of dumping all cached applications from memory. Rather irritating, I must say.
It's something Apple seems to be struggling with. iOS 7 prior to 7.1 did it, as did the initial release of 8.0. 8.1 and 8.2 never did it at least on my devices, but now it's back in 8.3. I think it's related to memory management. The device is either not dumping things from the RAM cache fast enough, or something is requesting way too much memory
in any case, the result is crashiness.