I upgraded after 2 years from the AirPods 4 model without ANC. The change was immediately noticeable, but least of all in the sound quality. Objectively, I'd say the new model has better bass and a wider delivery. The sound is more spread out to the sides, feeling more spatial. The most significant change when switching is the adaptive ANC. When walking across a field, I can hear the wind blowing and my steps in the grass, just like I was used to with the previous model. The moment a tractor drove past in the field, I thought how quiet its engine was, and after taking one earbud out, the huge difference in noise was apparent. I can still hear the music or podcast even though I don't have the volume high, thanks to the ANC.
I would never have believed how much of a difference it makes. It's the same with cars driving past on the road; the headphones turn a combustion engine into an electric one. In the settings, I have the noise cancellation strength set to the middle, so the headphones don't isolate me from my surroundings, but they beautifully reduce the ambient noise while I can still perceive the cars driving on the road nearby.
Another feature is the volume reduction during conversation. All you have to do is say "Hello", and right after the word 'Hel', the volume is lowered so you can hear the other person normally.
For someone who had AirPods 3 Pro, this is nothing new, but I can't wear in-ear headphones. I find sticking an ear tip into my ear absolutely disgusting, and on top of that, I sweat a lot, and then it makes a squelching sound in my ear when I move. Yuck.
I'm lucky that Apple's earbuds seem to be made exactly for my ears, and I can easily run, jump, or cycle with them, and they stay in place. The last, least successful but practical thing is the volume control on the stem. In short – it works. Of all the features, it's the least convenient. You have to find the right knack. Personally, I need three fingers for it: my index finger lightly presses the earbud into my ear, my thumb acts as a support on the stem, and my middle finger slides up or down the stem to adjust the volume. It doesn't always work on the first try, and you can't change the volume drastically; one slide just reduces it by the same amount as one press of the side button on your phone.
So, for a significant change in volume, you have to "stroke" the earbud several times in a row.
But it's doable and it works, it just takes a bit of practice. When cycling, this feature is absolutely brilliant and I missed it. In conclusion, when switching from the model 4 without ANC, I was amazed for a while because I'd never had headphones with ANC before. I was worried that if ANC was on, I would be isolated from my surroundings, which I would never want. Or that the feature would be off and I wouldn't be bothered to look for the switch in the settings just because it might come in handy at some point.
But Apple has designed it so that there's a middle option, where you use a slider to set how much the ANC should dampen the surroundings. During normal wear, you hear just as much as with the older model: the wind, cars, birds, the rustling of leaves. It's only when there's a significant noise that you can hear how the source of the noise is suddenly muffled. It's almost like magic, really very pleasant when walking and listening to podcasts or spoken word, and you're not disturbed by motorbikes passing by.