Quick update:

Things are going pretty well. And by pretty well, I've replaced a bunch of my home automation devices with HomeKit compatible ones, and I've installed an AppleTV. I'm pretty much all in at this point.

I've been keeping a running list of my impressions as I get used to the phone. I'd say there's almost a perfect split of positive and negative impressions, but overall I'm pleased with the move. I'll have to post those as soon as I write them up as full thoughts instead of quick notes.