I've been using iPhone 14 now for almost 2 hours straight.
Settings:
- Highest brightness
- Auto brightness off
- Reduce white point at 80%
- Dark mode enabled
So far, I am honestly not sure. I can say I don't have a headache or migraine or anything specific I can point to, but I do feel a bit off. (Could just be neck muscles being tense.) Of course, if I stared at my iPhone SE (2022) for 2 straight hours, I would probably feel the same way. I'm going to keep using it and give final feedback tomorrow, but I am not sure I'll be able to provide any meaningful data.
Aside from eye-strain, in general, this phone is amazing! I love how much lighter it is (weight) than iPhone 14 Pro. Everything about it is great. I think it'll be useable for me as long as I don't use it for long periods of time.