My Panasonic RP-HC500 headphones recently bit the dust after 2+ years of great service, and even then they only died due to a mechanical failure in the headband. I'd been very happy with their performance and longevity, so I was glad to see that the new RP-HC700 headphones had just been released. I've used them for a week now at my workplace, and I have to say that these headphones are a significant improvement over the old ones. There are three major improvements that matter to me:
First, the headband is larger. This was a literal sore point for me on the old headphones; the headband just wasn't long enough for my (apparently large) head. The RP-HC700 headphones fit me quite nicely, with room to spare on the headband.
Second, the ear pads are slightly wider, and they are tapered such that the back of the pad is wider than the front. This means the back of the ear pad holds flush against my skull behind my ear, without pressing against my ear... a much better fit than my old headphones, far more comfortable, and it can only mean less noise leakage as well.
Third, the passive noise deadening of the RP-HC700 headphones is far superior to the old headphones. With the active noise-canceling turned off and playing music at a modest volume, these headphones block out so much noise that I rarely notice anything going on around me. With the noise canceling turned on, the outside world might as well not exist.
If you want to know about the sound quality, I'll warn you that I'm not an audiophile, so I can't offer any deep info... but I can say that I'm quite happy with the sound quality for my purposes. I haven't noticed any distortion from the noise canceling, there's adequate bass and treble response for me, and volume range is great whether driven from my laptop or my iPhone.
Considering the improvements of the RP-HC700 headphones over my old headphones, I would have expected to pay something closer to Bose-level prices for these... but for $100, these headphones are an excellent value. If you're in the market for noise-canceling headphones, jump in and buy these now before the seller catches on and raises the price!