Bought these for the parents as they wanted to try it out, but most reviews seem to say it's ANC is on par with any other wireless earphones, the killer obstacle is not being able to play your own music so I personally wouldn't use it but you may be in a similar position where you can buy it for someone else as a gift.
As per usual, stack with your eBay gift cards and Cashrewards.
EDIT: Back in stock!
It sounds like an OK concept, but $300+ no way, gimmickish. But hey, selling point pitch, can you put a price on a "goodnight sleep".