Despite never having listened to any B&W headphones, I've had some real interest in these since their announcement, mostly because I've been wanting a decent pair of wireless headphones since getting an iPhone 8+. I've been following professional and use reviews alike, reading each post in this thread along the way. My lovely wife took note and bought me a pair for my birthday. Here's my after-5-hours-of-listening 2¢:
I'm honestly surprised that I read so many luke-warm or straight up negative first impressions about the sound quality. From the first few (streaming, compressed, Apple Music) songs I listened to, I thought it had a pleasant, inoffensive presentation. Nothing is shouty, nothing "stands out"—and I mean that in a good way.
My goal for these is passive listening while doing chores around the house, or late-night computer work, and because of that, I appreciate the smooth frequency response, from top to bottom, and its ability to really kick in on dynamics when called for. It gives me the ability to listen at a conservative level and not feel like I'm missing anything. I will say that they are pretty neutral in my opinion, lacking some of the "V" or "U" shape that some people may be after, and because of that they could be perceived as a little boring? But to me it's a clear, gentle presentation that I find enjoyable for casual listening.
The "case" is useless and the "fold flat" (in)ability is awkward, but I love the looks and build quality. I wore them for 3 hours straight last night and had no discomfort with the headband or ear cups, the latter of which nicely sit around my ears entirely.
I've listened with BT and USB and both sound great; no experience with analog cable as of yet. Having been familiar with so many firmware issues people have been experiencing, I updated and fully charged them before listening for the first time and have had no connectivity issues. I've only noticed that they switch off rather quickly after music stops, which is kind of annoying. They are thankfully much louder than all other wireless headphones I've tried, and I think lossless music through the USB-C connection sounded superb.
If you've read this far you'll notice I've said nothing about ANC... I honestly don't care about it and likely won't use it. I won't use these anywhere but in my quiet home after my family has gone to bed, so there's no need to muck up the sound with unnecessary circuitry. FWIW, I tried each ANC mode for part of a song and was pretty unimpressed with both ANC and the resulting SQ, but that's no different than any NC headphones I've tried in the past, which includes the QC35,1000X, Beats.
I'll likely write a full review once I've really lived with them, but needless to say I'm very happy with them and think I'll only get happier with further break-in of drivers and ear pads (assuming I don't run into firmware/BT/connectivity issues).