I love how easily they let me get lost in whatever I'm listening to. B&W headphones have always been special in that regard and for me, the PX7 is the best of the bunch.
I love how massive the soundstage is, and how that helps layer instruments and vocals together. I also really like how B&W handled the low end on these; it extends deep and hits hard without sounding congested most of the time, and is balanced pretty nicely by some extra energy in the upper range. The midrange isn't the star like it was on the PX but it's still present in the mix. Someone mentioned before that poorly mastered tracks suffer the most on these headphones and I agree—stuff with loose bass or grainy treble will sound harsh on these. As an aside, I often feel like I've been listening to different headphones than others on here; these don't sound dark to me at all, the bass isn't loose like it (comically) is on the XM3, vocals don't sound hollow and recessed, and the sound signature does improve by becoming more relaxed and even when plugged into a good source (aux, but also USB C). I don't know... I pretty much feel the same way as others did about the P7W, PX, and XM3, but I don't quite follow some of the criticisms I've seen here. Maybe my vocabulary isn't quite there.
The ANC is also plenty effective at knocking out background noise, and doesn't exhibit any of the sound-compromising qualities that Mid and High did on the PX. I've found the Auto ANC mode to work really well. Combined with how spot-on the wearing sensors have been for me, I literally just put these on often don't need to press any buttons on them (aside from adjusting volume). These are small things but they add up to an extremely convenient wearing experience. The lighter weight materials also do feel much more comfortable compared to both the PX and the P7W, but I miss the magnetic ear cups from those models. Despite being lighter the PX7 still look smart and feel sturdy (I also haven't experienced any of the build issues that others have mentioned).
I really like the app, too. Being able to pair, unpair, and remove devices from my phone is extremely convenient. I can switch between my iPhone and iPad just by pausing on one and playing on the other. Coming from the XM3 (which doesn't support multipoint), it's a very welcome change. And finally, the battery life is really, really good. I can get a week of daily listening in, then just continue listening via USB C for a little while and they're ready to unplug again.
So yeah, I think these are pretty special and I've been enjoying the hell out of them.