I might not be the most experienced audio consumer in the world but out of the experience I have with flagship headphones (most of the flagship Sony headphones ever released since the XM4's including cheaper models and most of Apple's audio devices). I really like these headphones.
PROS.
Audio: When it comes to the quality of the audio itself these are better than all my previous pieces. And it is not a matter of recency bias as I directly compared them to some others at that moment. (that is before I created parametric EQ's for specific types of music and had a neutral EQ for all headphones "out of the box sound") and it was already better which is to be expected by a company like Sennheiser (It is also notable to say that this is with Hi-Res 24bit / 96kHz enabled for the Sennheiser's through the app)
The same songs were compared for all different audio devices with "out of the box sound" and later EQ personalization for the specific different kinds of music.
Classical music: Flight of the bumblebee, Bastilas Theme, 24 Preludes In B flat minor and 1812 overture
Alternative: Old yellow bricks, Teenagers and undercover Martyn.
The gap between the headphones slightly increased in the favour of these headphones after I had the chance of playing with the parametric EQ which is just SOOOO AMAZING, so much better than band EQ's (the ones with the dots you can slide up and down) and so much more costumizable, the sound that I get feels so much more me.
SmartControl+ (the app used on a mobile device to connect the headphones) Is great, I absolutely love the app which genuinely impressed me as I previously believed the Sony sound control app to be as good as I was going to get, but the SoundControl+ app is great, I love it, switching between different parametric EQ's feels more seamless and great, the app itself feels less cluttered, although I must admit since I am not the owner of other Sennheiser devices I am not aware of how seamless the transition from one device to another is.
Battery life: It is great and it absolutely delivers in its promises, there is not really much to say about it other than the fact that it does as it says.
Case and extras: The case feels really high quality and I love it, it might not have a fancy magnet but the zipper feels high quality and thanks to it's extra pouches and spaces I can oftentimes fit a few extra cables or needed dongles in there and put the case in my bag as it is instead of bringing a separate cable pouch.
it of course comes with it's standards Male-Male USB-C charging cable (which feels high quality and great overall). a 3.5mm jack cable. The BTD 700 dongle. And the attachment for the airplane's connector which I can't seem to remember the name of.
Comfort: If there is anyone that is going to be able to confidently talk to you about the comfort of headphones I believe I can definitely be the one. I listen to music (or other audio) 9+ hours every single day. Either while I am walking, running, studying, playing video games, cooking, reading a book or simply just standing. And even though of course like every other pair you might have to adjust them every couple of hours to ease a spot that might have gotten sore these headphones absolutely are comfortable IF adjusted well.
CONS:
ANC: I have not yet on any flights with them (update incoming as I do have a flight in a few days) they do struggle with blocking white noise (bus engines, airplane engines or other similar noises) and I know that because I do happen to live quite close to the airport so yes I do hear the planes. BUT, even though the ANC is not by any means AMAZING, it is okay, good even. It does it's job and you will absolutely not be getting annoyed if you have the ANC cranked to the max (the ANC is scalable from 0-100%) and have the headphones on appropriately over your ears so they form a proper seal.
UPDATE:
I recently went on a few flights with stops and decently long airport waiting periods and I must admit the hard truth. these are not traveling headphones... I had the pleasure to have been seated directly in the top of the rows as far away from the airplane wings as well as directly next to the wings on different flights and while my experience in the top row was okay, the seating next to the wings was not. There is the constant hum of the engine that can very clearly be heard and while many people might not notice it as it is not particularly loud with ANC turned to the max it is there and it personally drove me CRAZY.
