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I bought these headphones for my Dad for his birthday after having extensively tested a whole range of noise-cancelling headphones in a number of electrical & department stores. I had originally intended to buy the Bose Quiet Comfort 3 headphones, but found these to be much better value.
First the best bits: The ear of the headphone swivels to allow the headphones to be more easily packed (important, as I knew that they would be primarily used for long plane journeys) and they come complete with their own protective carry case. Like the Bose headphones, these require batteries for the noise-cancelling function to work. If your batteries run out in the Bose headphones, you can no-longer use them, even without the noise cancelling function, which was a big drawback for me. However, these Sony headphones still work if the batteries die, just without the noise cancelling function. They take standard AAA batteries, so it is easy to carry spares in the carry case.
I wouldn't say there are 'cons' to these headphones, but it is worth noting that the sound quality and noise cancelling ability is inferior to the Bose QC3s. However, they are 90% as good for less than a sixth of the price, so much better value!
To give some perspective, I bought these headphones in 2012 for just over £50 from Amazon. I have seen them for double this price, so it is worth shopping around.