I’m coming from the 11 so mine is more of an outlier than the 12. But I can also chime in from being a viewer of tech channel comparisons.
1. Battery: very noticeable and substantial improvement from the 12. The very best competing flagships of 2022 don’t even touch the 14 PM. Starting on the 13 PM, Apple has pulled away in battery life (interesting to note the 14 PM has the smallest battery for a flagship).
2. Display is about as sweet as it gets on a smartphone — you will notice the difference. One display metric measuring group said the 14 Pro is the best smartphone display they’ve ever measured. Also include in this upgrade direct sunlight brightness performance.
3. If you are a casual pic/video user, you’ll notice a difference but unlikely to be substantial. But If you like to take closeups, difficult shots such as night or sunlight/shadow mixes, like to sharpen pics after the fact? The 14 PM is a BIG! difference. Industry best in many categories of camera.
4. The most unmentioned feature you’ll actually definitely notice, speakers. The 14 PM speakers are definitely industry best by quite a lot including over the 13 PM. I use my 14 PM both as a speakerphone and as a music loudspeaker in a pinch. I’m not saying it’s OG HomePod good

but from a smartphone perspective Apple has kicked it up two notches on the 14 PM speakers.
5. The snap of the A16 is good but that’ll be not regularly noticeable. However, I’ve seen the Bluetooth connection performance increase noticeably but certainly not out of this world different.
6. Always on display. Noticeable and functional but won’t be a big deal to many. Depending on your iPhone use case it could be a big difference for you (or not).
7. If you commit to using the dynamic island (break yourself of the old app switching methods) then it’s very noticeable. It’s a BFD to me. Some of my most common multi app uses: music and texting/surfing, phone call and texting/email/internet, (while driving) music-Apple Maps route display-texting(via voice). The dynamic island provides a much simpler way to navigate apps. Just note that it is limited but I expect it to grow in function (why not have the option to put the last app used in the island)