Just got one last Wednesday (1/17). I came from a 6s Plus. The notch doesn't really bother as much as I thought it would. I thought it'd bug me watching videos landscape, but it just frames it like a regular iPhone. Do I miss the real estate of the Plus? I do. Now to the gripes:
1. Why does closing apps require a force touch for the red icon and then swipe away? Just get me to multitasking and let me swipe them away like on regular iPhones. Granted the swipe up gesture is designed for going home, but can't the system differentiate between when you're in the multitasking screen or not?
2. Going back in landscape. On a regular iPhone, when in Safari and wanted to go back a page, I'd just swipe and it would go back. Now my thumb has to go further back to swipe. It's not as fluid. Still getting used to that.
3. FaceID works fine, but as someone stated earlier, it doesn't work first thing in the morning for some reason. It is generally slower than TouchID, but it's fast enough. I don't mind it.
4. Control center being summoned by going to the top right is weird. You don't have to get it precisely in a specific spot on the top right, but you can't be off even by a little to the left.
Those are my gripes. I thought that coming from a Plus would be easier, but since the screen is taller, it's about the same as far as moving the phone up and down my hand to adjust the grip to reach the top, bottom and edges. I rely on reachability a lot. However since it's not as wide as a Plus, it does help day to day. I have about 9 days left to make a decision whether to keep it or return it for a Plus model. As of now, still keeping it, but like 70/30%.
Edit - Maybe a double tap on the home screen to stop the icons from jiggling when re-arranging them instead of having to press done would be an improvement. I thought I'd miss the battery percentage showing on the menu bar, but since the battery life has proven to be great, I don't miss it as much.