I'll start with the bad. you have this weird bulky amplifier thing that gets in your way, ends up hooking on to things, and just adds extra bulk to your pocket when you aren't using your generic MP3 player. The bulky amplifier thing takes battery, which is really annoying, so now I have to carry a spare battery around with me. Durability isn't superb either, have had it only for about three months and I am getting intermittent sound in my right ear.
Now for the good. the amplifier thing works, I get absolutely brilliant base out of this. The bulk is hung from the neck so the weight isn't that much of an issue. the inner ear part works brilliantly, the noise canceling is brilliant, it totally makes those tube rides bearable. Overall sound quality is one of the best I have heard from headphones.
Conclusion. The negative points of bulk and extra battery carrying is set against the extra base and sound quality the amplifier affords you. Infact, so much so, it hardly bothers me at all, I would even say it makes me a little affectionate to it for the extra hit I get from the music. Carrying a small AAA battery is also little price to pay. Noise canceling claim really works, and makes the base sound great. Durability-wise I wish it would last me a little longer, but headphones just seem to be going the way of mobile phones - exchange them every year. I bought these headphones for £35, and the price has fallen quite a bit in three months. These are well worth it, even with the hassle of the bulky amplifier thing.