Wondering who else is having issues with the messaging app locking up. I first tried rebooting the device, then resetting all settings, and last I did a clean install of iOS 8 beta 2 using the IPSW from the developer portal. It definitely does not seem to have to do with the data that was on the device as it locks up post restore without bringing any data back to it. I have an iPhone 5 on Verizon.