I set the new phone up, charged it up, then left it sitting on my desk overnight. This morning it required a soft reset to bring it back... yikes! It hasn't happened again since, but I'll see what happens tonight and decide what to do tomorrow.
Had it occur once during the setup process but hasn't occurred since so fingers crossed that everything is ok.
It seems to have survived the night, so yeah, hopefully it's not a bung one again. I'm counting on the announced early December patch to deal with minor reset issues, but the previous phone was just so bad it was unusable.
I had it again as well - I've been reading through replies on other forums with people taking the phone back but the same thing occurring and there are also HTC people who have experienced the same problem which leads me to conclude that maybe it is Windows Phone 8 rather than the hardware. With that being said, I've since uninstalled Facebook, Angry Birds and the weather application thus so far I haven't experienced any freeze ups.