I have had big, bulky Bose noise cancelling headphones for some time now and really like them and found the noise cancelling to be amazing for travel or just for focusing when working on projects. When I found out that Bose had wireless noise canceling headphones, I had to try them - so I bought the Bose QuietControl 30s which are somewhat similar to these JBLs. The Bose wireless earphones were fantastic at noise canceling, had nice sound quality, and they fit very comfortably... but their Bluetooth wouldn't connect with one of my devices. That frustrated me, so I looked at other in-ear wireless noise cancelling headphones and found these JBL units. I figured it would just be a bonus if they happen to work as well as the Bose since they are 1/3 the cost.
I still have both brands here and have compared them, and I have to say that the JBL is really disappointing when it comes to noise cancellation and the comfort of the fit. They do cancel some of the sound, but not nearly as much as the Bose QuietControl 30s and it doesn't give you that sense of being in a really quiet place when you put them on.
Also disappointing was the fit of the JBL earbuds and included silicon pieces. First, the design is pretty confusing and it is frustrating to try and change the pieces in and out because it feels like you might rip them moving them around. Second, even though the JBLs include 2x as many size options as Bose does, none of them were comfortable in my ears. I actually ended up trying the Bose rubber ear pieces on the JBL and that was the most comfortable option! (If you keep the JBLs or get them as a gift, I highly recommend you get some Bose StayHear+ silicon ear pieces to have a more comfy fit. They aren't designed to work with these JBLs, but they worked really well in my short testing.)
I even installed JBL's app and updated the firmware -- they simply don't noise cancel very well even with the newest update installed.
The design of the neckband is another problem. JBL put all the weight on the back of the band, so if you lean back at all while wearing these - such as on a bike, in the car, or sitting at your desk - the JBL neckband falls off the back of your neck and begins to slide down your back. Clearly, JBL noticed this problem in testing, because they include a little "addendum" instruction sheet that tells you how to clip on some cheap looking plastic neck grips that do help it from sliding off. They aren't uncomfortable and they seem sturdy, but it seems to me the design flaw was even obvious to JBL but they decided to provide a slap-on fix rather than fixing the basic design.
What do the JBL do well? The sound is very good - not too bright, not too bass-heavy. If these were less expensive and if I didn't care about noise canceling, I would have probably kept them. Unfortunately, I'm spoiled now to the comfort and serenity of the Bose QuietControl 30s and am keeping those. I recommend you skip these JBLs and consider other options.