Good build quality, and good non boomy sound quality, especially for the price these do well on sound.
Noise reduction at this price/range level is basic, and whilst it does do SOME REDUCTION , it is about 25% as effective as top of the range, if you want strong noise reduction you need to be looking at £ 150 + phones, like Audio Technica or BOSE or Sony 5000 model.
If you want close to audiophile sound and good NR, then look at Sennheiser PCX350 / 450 , these offer the best sound for this type of phone, however NOT the best noise reduction, again Bose / AT / Sony offer the best NR without any shadow of a doubt. ( My personal Favourite is Audio Technica 7 , NR as good as BOSE , but better sound quality ( less artificial ) and cost < 50% of BOSE price. )
Having head BOSE / Audio Technica , I can safely say these are no where near as good, neither in sound quality of noise reduction, however, they still have their purposes, and for a low cost NR phone they are much better than the non branded alternatives.
If you want to spend a bit more, the Goldring NS1000 phones are better for NR.
If you can spend around £ 150 the Audio Technica / Sony are unbeatable for NR and high end sound.
Conclusion: These JVCs are ok, not bad, offer a little NR and no problem with audio quality.....for the price, they are decent and much better than not having a NR phone at all.....
To sum up, these are 75% of BOSE quality, for 15% of the price.