My wife's and mine are the same way. We noticed a reboot here and there, but more recently it's not uncommon for it to reboot every 5-10 minutes for a few hours straight or 2-3 reboots back to back. It's doing it all the time while on calls and texting.
My cell is my work and personal phone, only phone I own outside of VOIP. It has dropped very important calls and rebooted in meetings to the point people ask me what my phone is doing after seeing it keep lighting up with the HTC screen lol. Because of this, I have to say it's in the running for the shittiest phone experience I've ever had.
I asked VZ and they said some apps can cause this and there's nothing they can do. I did a reset and installed NOTHING and it still does it.