There are a lot of posts bemoaning the new update, but I am very pleased that Vodafone has provided an upgrade from Lollipop to Marshmallow for the Ultra 6, so I wanted to offset all the negative comments here.
My recent experience with OTA upgrades with previous phones hasn't been great. It seems that once a phone is no longer in the shops (Motorola and Sony), they stop upgrading it.
I'm very pleased to have a newer operating system on my year old phone, and am pleased with the improvements especially the overhaul of app permissions.
I did have to do a factory reset, but that solved some on going issues I had with Lollipop, and with so much changing under the skin of the OS it's unsurprising everything didn't just work.
Fingers crossed for a Nougat upgrade a few months after Android O(reo?) is realeased.