Pros: They are cheap.
Cons: They don't cancel noise!
The bottom line: Don't buy if you want noise cancelling headphones.
I bought these just prior to a transatlantic flight. I wanted to reduce the background noises to a level where I could enjoy a movie without having to increase the volume to ear-damaging levels.

In flight, I wasn't able to detect any noise cancellation from these headphones.

I tried wearing the buds naturally in the ear, and I tried pressing in the buds in my ears by holding the short stalks to achieve a total seal, while my wife switched the noise cancelling circuit on and off.

If an effective seal is achieved in the ear, then noise will be reduced like any other sealed in-ear headphone. But the noise cancelling button had no noise-cancelling effect.

When the noise cancelling circuit was switched on I noticed a volume increase, or perhaps a compression effect, on the source sound. If music is playing then of course outside noise will subjectively sound quieter since the music becomes louder. This, however, can be achieved with any headphone by turning the volume up! If NO music is playing and the headphone is plugged into a source, any hiss from the source is increased. Without a source, it is clear that the noise cancelling circuit introduces a hiss of its own.

Hence the noise cancelling circuit on these headphones is worse than useless, in fact introducing noise. Any subjective noise reducing effects are due to a loudening or compression effect on the music, which in no way can be described as noise cancelling. In fact, loudening or compression is exactly what I wanted to avoid: increasing the volume to ear-damaging levels in order to overcome background noise.

I see this as nothing less than a wasted purchase since I bought them for their noise cancellation. I make no comment about sound quality itself, since any test of sound quality on an aircraft is irrelevant unless the noise is cancelled.

Call me old fashioned but if something is sold as noise cancelling and does not in fact cancel noise, that is mis-selling.

I'm not inclined to write one-sided reviews but I can't do anything else in this case.