So my 920 has been mostly perfect, with an occasional freeze (maybe averaging 1 per week). I have many random apps loaded.
However, I bought my dad one at the same time too, loaded basic apps for him and he has not had one issue. I setup up Hotmail and his company's Office 365 and he is loving life. He reports no issues and 2 day battery life.
I'm guessing all this is app related. The hurry to get apps done for Win8 is probably to blame, not the OS, firmware or hardware.
Same thing happens to me when ever we do an OS upgrade at work. SMS/SCCM installation packages are rushed through repackaging and testing, (for say the upgrade from XP to Win7) and this results in poor quality. Its seems at first like the new OS is to blame, but its actually, say, an app trying to lock a process like it did just fine in XP, but Win7 wont allow because of some new permission.
Factory reset and only run apps in their 2nd or 3rd revision for Win Phone 8 and I bet you'll run perfect.