I am very happy with the fit. I think the stability bands were a great idea and make what is a fairly bulky device far more stable than I would have expected. I was also pleasantly surprised by the noise cancellation, it's still not as effective as the noise cancellation of my 4+ year old Bose 700s, but it does work in some specific use cases while still letting in some annoying frequencies (even after running a successful seal test). If you're a smaller person with small ears (I'm 5'9" with fairly average ears from what I can tell) I do not believe these will work for you. I fear these may have been subject to the common failure of western designers using QA testers who tend towards the average american male traits.

The software customization is very disappointing. No matter what I try, switching modes is always accompanied with the robot voice saying what setting it is now in even when you only have 2 distinctly different, easily recognizable modes that are self evident without the interruption. What makes it worse is that it will sometimes accept my input, return the robot voice saying I'm in "aware" mode (for example) but the mode settings are still in "quiet" mode until I resubmit the input and the robot repeats the same mode as the change is actually made to the mode setting. I've also had issues with earbuds not knowing the difference between being in my ears or set on the table and continuing to play audio in the background when I'm expecting it to be paused based on the manual.

The most disappointing element is the poor quality build of the case. The case is essential to the product, the earbuds are useless without it, so the attention to detail should still be there for such an integral element of the product. Difficulties taking out the earbuds with long nails is something I can understand being missed during QA tests, but the hinge of the case is poorly designed and executed to a shocking degree. It's immensely wobbly when closed and feels like it could break with a single drop at the wrong angle. These Bose buds are $50 more expensive than the current high-end earbud "standard" (the ones that are optimized for iOS exclusively) which, in contrast, has the best executed earbud case I've seen so far: the hinge is actually made of a material that is up to the task of functioning as a robust hinge at a small scale with high use.

After the impeccable experience I had with the Bose 700 headphones (which I would give 4/5 because they're, once again, not good for small heads), I was expecting a comparable degree of build quality, and that may have been my own mistake. I'll be keeping them, they're functional earbuds with the expected Bose audio fidelity, but it is a very disappointing build quality that I am simply hoping won't lead to these becoming e-waste due to a bad drop or the hinge just giving up what little it had to give it begin with (although I imagine I could return them to be refurbished if that sad future would ever come to pass, which is of come comfort).

These are really good earbuds!
I got both these and the Sony WF-1000XM5, and as a BB total member, had some time to make the decision between the two. Went on 4 flights and compared overall performance between the two options, and the Bose came on top on almost everything besides one feature, at least for my individual needs (i travel a lot and mostly use the earbuds in flights):

1. Active Noise Cancellation: The Bose are way better in the ANC feature than the Sony, especially in flight, but even overall in a noisy environment, with high volume conversations in the background, The Sony were good, but in my opinion not even remotely close to the Bose.
2. Comfort in the ear: I liked the Bose ear feeling more, they're not as big inside the ear and the ANC makes it that they don't have to be pushed all the way in the ear to function at a high level. the Sony has this foam like material that expands in the ear, which on the positive adds some more blockage to the noise, but on the negative after a while you start feeling in in your ear.
3. Sound quality: I think the Bose are a better sound overall, both on phone calls and on music. Watched several TV shows and a Movie with both, and the sound coming from the Bose was more crisp and rich but the sound from the Sony was more bass and deep, so i guess it's a matter of individual preference.
4. App: having both apps, i can definitely say they both suck, but the Bose app sucks a bit less. I had some connectivity issues with the Sony on both my Samsung S24 Ultra and my Lenovo Laptop - maybe it was a local problem with the pair i had, but the BT kept disconnecting from the earbuds perspective once every couple of hours. No connectivity issues with the Bose.

The only definitive advantage i found with the Sony earbuds was the microphone. the mic on the Sony is way better when having a phone call when compared to the Bose. the Bose have this echo resonance in the background but the Sony sounds good and clean. Verified with several calls to people and getting their feedback on how they heard the conversation from their perspective.

Overall, these are great, and for my individual needs the Bose were just a bit better than the Sony ones (higher need for ANC during flights and emphasis on sound quality).

I want to love these headphones, I promise I'm not a hater, but there is one huge problem with them.

The audio quality itself is best in class, the immersive audio feature is incredibly well done, and makes tracks dynamic and punchy and very enjoyable. I love it. Then there's the noise cancellation, which given these are earbuds and not over-ear cans, is just incredible. I am very happy with the performance of these earbuds. That is to say, I'm happy when they're actually working...

Which leads me to the issue.

The Bluetooth performance is just awful. I don't know if Android users have the same problems, but on iOS the issues are endless. I routinely have to disconnect and reconnect the earbuds 3~4 times each session to get a stable connection, and even then, it might drop out eventually. I cannot use my Apple Watch and these earbuds at the same time, because the connection won't work at all. There is a reset button on the case for these earbuds, which I find myself using many times a day as I try to get them to work. Unfortunately, this issue makes the process of using these headphones absolutely infuriating.

Further, personally I can't run with these headphones, as they don't stay in well, but that could just be my wonky head - you might not have problems. However, if you're a runner, I recommend checking this and consider models with wrap-arounds.

Further (and you may not agree with this), I am of the opinion that any sports-oriented headphones should not use touch-based technology - they should use buttons. Touch technology is frustrating when exercising because it is too easy to brush up against them and cause the device to issue inputs you don't intend. Can we please just have a button for this price? I feel like I've paid enough for this.

I want to love these headphones, because the sound quality is excellent, I simply love using them (when they're working), but I just cannot see how a pair of headphones this expensive should have Bluetooth that functions so poorly, I've had earbuds at a quarter of the price that are far more stable, so I just don't consider it acceptable.

Your mileage may vary, but I highly recommend you test these if possible prior to purchase, or consider a different model or make entirely.

The Bose QC Ultra Earbuds are a story of two halves. Pros; Excellent noise cancelling, commuting on busy trains and the tube is a breeze, Excellent sound quality, Lightweight and comfortable in the ear, not too bulky and stay secure during workouts.

This is where the pros end. Although initially they connected with my devices easily and quickly, that soon stopped and I was plagued with constant connection issues. They’d randomly drop from a device, the sound would swap between the earbuds for a few seconds, audio glitches like beeps or ringing started and no number of resets would fix. The biggest issue then came when the left earbud randomly became about 50% quieter - all this within a month of owning the product. Unfortunately this put me outside of the Curry’s 30 refund window (a shockingly short window which I’ll explain later). Bose agreed to send a replacement which took about 5 weeks to arrange and have the new pair. This new set was even worse than the old one, they couldn’t hold a connection for more than a minute without completely disconnecting and wouldn’t reconnect for about 5 minutes, completely unusable. I’m now waiting for another replacement from Bose and hopefully these work.

I am now stuck potentially cycling through new earbuds with Bose until I hopefully get a set that work. Curry’s refund window being so short for such an expensive product is shocking. I’d refund these in a heartbeat if I could as they are genuinely one of the worst purchases I think I’ve made.

Overall I wouldn’t recommend, just the fact that I’m onto my third pair within a couple of months speaks volumes about the longevity/quality.

Shame on Bose for releasing such a shoddy product.