I have played these (Airpods Pro) for a few hours now in a lot of A/B comparisons.
People who say they don't notice a difference from Airpods 1/2 vs Pro - I don't get that. I just got them and the bass is WAY better/richer and the sound much fuller than the Airpods 1/2. They are also plenty loud. I can play them less loud in my ears than the Airpods 1/2.
The key is to get the fit right. You need to get a seal. The ear tip fit test (truly wonderful, every earbud company should copy this as seal is so key) helps make sure you got it right. What I have found however is in one ear it's a little finicky, so if I use the stem to change tracks, etc, I can dislodge the seal. You really have to push in the buds a bit to get a good seal. Once the ANC kicks in you have a good idea if it's solid.
That's not unique to Apple though.
The tips are a unique silicone, kind of thin, but do securely snap to the device.
(I am wearing large).
Also, the pods respect any EQ setting you have set on the phone. So. try something different! I use "rock" which may be TOO bass forward. Latin sounds better...
And no, these things are not falling out - they are super light so they stay in there. You almost forget they are there. Vastly better than Airpods 1/2 in that respect. And those fit me well, but felt like a stiff wind could jostle them out. Not so with the Pros, which also have a much shorter stem to catch on stuff like toques/winter hats.
Playing an Airpod Pro in one ear and an Airpod 2 in the other I notice the bass and sound is much more full and rich on the Pro(s), but the overall sound characteristic is similar. In order words, imagine an Airpod 2 with a lot more tight bass, and decent amount of additional/wider clarity in the highs. It's quite good. But others (Bose QC35) sound better. It's.... VERY GOOD. Not stunning. (airpods 1/2 were... ehhhh - they are flat and tinny in comparison, honestly. Very mids heavy.)
As for the "pressure". I do have sensitive ears. It's a little off-putting like any ANC headset. The transparency mode does help reduce that feeling without ruining the sound. You still get the full effect (bass and all) but can also hear around you. It's quite nice. But transparency mode can kind of mess with you too: your ears feel the pressure of the buds, but you don't hear it. Then your brain thinks "huh?". I would use transparency only when needed.
With full ANC on it can make your ears feel full. There is venting/pressure equalization but it's not a panacea. If you can handle in-ears you'll probably be ok.
Bottom line - they are a huge improvement over the original Airpods. But the original airpods have a place if you don't like the physical feeling of your ears being sealed off.
EDIT: I want to add, that although they sound, to me, a little to lot better than Airpods 1/2 (much more bass, a slightly wider range of sound), and the ANC is excellent, I just put on my Bose QC35s. The ANC is similar enough. But the sound on the Bose still is better. Especially in the highs. It's just much wider dynamic range all over, with tighter bass.
Then again, they don't fit in my pocket.
Bottom line: a huge improvement. Great sounding earbuds. they don't fall out. The ear fit test is critical to good sound and is a first. Not as good as full on ear cans but who that's rare.