I always wanted to buy noise cancellation headphones but I was reluctant to do that given that they are pretty expensive. Two months ago, I did purchase one. And I only regret not buying them as earlier as I could.
Do you think travelling in an airplane or a train for long hours can be tiresome? Especially if you end up near a crying baby traveller or chatty fellow traverlers. These headphones can save you the trouble and make the trip much less irritating. I travelled to Berlin for 4 hours trip on the train, and using my headphones was outstanding.
Your company has an open space office with people talking all the time around you, and you want to focus? or maybe you work from home and your kids are making noises in the other room, your headphones are there for you.
In a nutshell, it is worth it. I have Bose QuietComfort 35 II and it is great.