I like that I can use an iPhone SE with just one hand because it's short enough to reach the top with my thumb. That comes in very handy when you're carrying a sleeping baby.
The Huawei gesture is a sideways swipe on the navigation bar (it shrinks to the side you swipe towards).
The main problem I have with large phones is that they won't fit into my pocket. Sure, I could get out the needle-and-thread and sew myself some larger pockets, but I shouldn't have to do that. I'd much rather just have a smaller phone.