my $.02
My 6p has been great on Verizon with a few exceptions. If you need a nano Sim, don't go into the local Verizon store. This was a nightmare (i.e. phone is not auth on our network, you could be a terrorist, etc, etc) and ultimately I ended up walking. Called customer support and they were amazing and overnighted me a new Nano Sim and waived the $5.99 fee.
In the meantime, I just cut my micro sim with scissors and it worked mostly perfectly. Look online, plenty of templates/vids. No skills necessary.
As others said, make sure you enable Advanced calling in your VZW account so you can use voice and data at same time. It's 100% free and does not in any way alter the grand fathered Unlimited Data plans. Call quality was surprisingly even better than before and the 6p was amazing out of the box. No noticeable impact to reception or battery life on my end. You do not have to download any VZW bloat to do this. Just sign into your VZW account and add the option.
I was also getting garbled text messages from VZW when someone would leave a voice message. Just to rule out the sim, I swapped my micro with the new Nano when it showed up and I no longer receive those text messages. I now forward missed calls to a 3rd party VVM service and that also helps.
Follow these steps (more or less) and you have nothing to worry about. The 6p is hands down the best phone of 2015, so don't wait any longer!