The iPhone SE is one of the best of the very few small phones still available. It would be a significant downgrade from an iPhone 6, isn’t a quantum leap over the iPhone 5S and should only really be considered if size is the overriding factor.
one-day battery, good rear camera, decent screen, easy to hold, easy to fit in a pocket, fits in existing iPhone 5 accessories
very small screen, edges are hard on hands, looks like an iPhone 5 or 5S, selfie camera isn’t great, no expandable storage or removable battery