Out of the box they are very sharp on the treble. I don't think I would be able to wear them for long, although they are fine for skyping. Lowering the treble by about 7db's and they become practical. I found 3 layers of toilet paper also does this fine. However properly equalized with a parametric - highly adjustable - equalizer (ie. Electri-Q plugin or the Ipod/Nano/Sansa free 3rd party firmware, Rockbox) by accurately taking out the sharp treble peaks, filling in a notch and flattening out the low bass then they sound very good indeed. Search google for "headphone equalization headfi" for more on this. More expensive headphones have flatter frequencies and don't require so much adjustment.
For £20 they are a bargain even unequalized so long as you've a little tissue paper handy, but with equalisation they are really something else, just beautiful. I discovered them on the forums where they are sometimes said to be giant killers; and that's just with treble adjustment. I'm thinking of getting another simply as a spare as the price is such a bargain. The parametric settings I need are 30Hz +6db q=2.8 (bw=0.5), 5000Hz +4db q=5.4 (bw=.25), 8000Hz -8db q=6.4 (bw=.2), 12400Hz -6db q=6.4, and a touch decrease on overall treble (to taste, in my case -7db). Rockbox uses 'Q' but other parametric equalizers use bandwidth (bw) and they are not the same numbers though they have the same function of defining the width/spread of the targeted equalisation.
Keep in mind that they are semi-open: a lot of sound leaks out and they aren't much good in a noisy environment. Supposedly this increases soundstage. And they have a lot of that.
Out of the box, 3 stars. Toilet tissue= 4 stars. Equalisation = 5 stars.