I just use my iPad mini 2 LTE 128Gb. I use the Freetone app to make calls and do SMS messaging to non IOS phones. I do not make calls with headphones. Instead, I hold the bottom of the ipad mini to my ear, and the top closer to my mouth. The iPad does not have ear rejection, so I hold the microphone end out a bit from my head. Yes, I wish for a better camera, 2 gb of RAM, and pencil support. I occasionally want something smaller when I am biking, running, paddling, sailing. The new watch sounds interesting, but I do not know whether it can work with an LTE ipad instead of a phone.
The mini is pocketable in my dress pants, but not my jeans. It is the perfect size for gaming, reading, everything.
I have considered buying a used Iphone SE for occasions when I need smaller.
Regarding photos, I will pull out my Canon SLR and lenses when it is something I like to shoot. For family events, I let my wife take them on her Iphone 6. Wildlife, birds in flight, airshows are not great photo subjects for iphones. 50D with 400mm 5.6L is much better. 7Dmk2 would be even better.