These headphones are a great value. There are very few reviews of these on the web regarding sound quality, so I shall do my best to address this. I've compared these to my Sony MDR-V150s which are similar in design and price to these Panasonic headphones. The Panasonics have hard hitting bass and also better highs as well. They sound warmer and more clear than the Sony headphones. The Sony phones sound kind of muddy in comparison. I also played some test tones and found the Panasonics will reproduce a 20 Hz test tone just fine. The Sony unit would not reproduce the 20 Hz tone at all. These also have 40 mm drivers and neodymium magnets compared to the 30 mm drivers and ferrite units in the Sony. The frequency specs are much better on the Panasonics (10hz-27khz vs 18hz-22khz with the Sony) and based on my own tests seem believable. Remember the Sony units would not reproduce the 20 Hz test tone despite the specs indicating they are capable of 18 Hz, which in reality they are not. So overall for the price you pay these are great sounding headphones and are in fact better than the Sony MDR-v150 in terms of sound quality. They also are pretty comfortable and have padding at the top of the headband which the Sonys do not have. The only area the Sonys win out in is in the quality and length of the cord. The Panasonic cord is thinner and only 4 feet long. I would recommend an extension cable with the Panasonics if you plan to use them with a home stereo system. The short cord length is advantageous however for use with portable devices like mp3 players since too long a cord just gets in the way.
Keeping it short and sweet. I really like these headphones. They don't hurt my ears and I think the sound is really great. Specifically, a lot of attention was paid to emphasizing the bass. I had to turn off my mp3 player's bass boost because it was a little too much bass with that feature and these headphones.
As far as cons, I do think they are a little stiff at times. Maybe because they are new. Perhaps I have to break them in. Also, the left side is hard to adjust. Maybe that's just my headphone set, though.
Anyways, I have a thing for pink and green, so I loved the color. I use these just around the house and they work well. I'm not an audio expert or anything, but I do have Audio Technica noise cancelling headphones and I think these Panasonic headphones are just a step below the sound produced by my Audio Technica. Again, I'm no expert. Just my opinion.