Build quality is phenomenal and they're surprisingly low profile. My first pair actually had a problem with the touch interface and B&O not only replaced them, they expedited shipment so I'd get them in time when I explained I had a long trip coming up - so great support.
The only drawbacks are:
- they're on-ear which takes some getting used to, especially early on before the band takes shape to your head and can press to your ears. However, the padding is very soft and even replaceable! I now believe on ear produces the best accuracy as there's no acoustic reverberations and feedback that you can sometimes get with over ear. However, over ear is more comfortable and even after breaking these in, you'll still get ear fatigue after some hours of use. That being said, I've fallen asleep for hours on flights wearing these and not even playing music as the noise cancellation completely eliminates engine noise and most external sound in general
- they cannot be charged and used at the same time, even if using the wired lead. This is probably the biggest drawback though at 14 hrs play time and having a replaceable battery, this can be mitigated
- the previously mentioned drawback of not having noise cancellation when using them wired is annoying because the noise cancellation is exceptionally good
- they don't fold in any way, so you need to consider how to carry them if not in use. I usually just extend the headphones and keep them around my neck. In general though, you'll find the higher quality headphones won't be foldable as that's an easy point of failure
They're pricey but I've tried a number of other brands and the features/sound quality of these are far and away the best to be had. Not to mention, they look great when worn unlike most others that look cheep or goofy in their bulk. Highly recommend
Amazon has them on Prime: https://www.amazon.com/Bang-Olufsen-Wireless-Headphone-Cance...