Design&looks
Very discrete, solid build, quality materials. Attention! May be falling out of your ears; there are utterly no adjustments whatsoever; you could end up adding extra padding to no avail. Be careful - test before you buy to avoid frustration; Sennheiser does NOTHING to help. If you have other earphones from then, spare parts do work (eg. from MX75 the green rubbery thingies do fit), may help to solve the problem.
Cable feels quite rigid which contributes to the earphones popping out. Especially in the winter, when the cable goes inside the jacket and just a small piece remains between the ear and the collar of the jacket.
Sound
Very "mature" sound. Crystal clear, well controlled base, quite neutral. A good fit with the ear is critical though!
Extras
They come with a leather case, airplane adaptor, extra pads. What I think about that? Waste of time - I'm not going to be carrying around an extra case 3 times the size of my mp3 player. A very trendy clip to keep the earphones attached to your garment - totally useless (tight, finger nail breaking; solution - simple clip from older nokia phones works light years better).
Overall
For this money a bit disappointing - this is the S-class of Sennheisser for portable devices. At almost 140 quid I'd be expecting more. For the fifth of the price one can get the younger brother (mx880) - a very interesting alternative.
Would I buy them again? No. Sound great, but fall out of ears and way too expensive for the overall delivery.
*****Jan 2012, update: after few weeks of usage: the converter does not fit plugs on planes; at least not on the 747-400. Case turns out (actually) quite crappy and useless - cable needs to be bent at sharp angles to fit in snugly (unless it is one of those use-you-brain-mind-games; no idea; having iq same as my age, I stay away from these puzzles). MY EARS got adjusted to the shape (finally), they are not falling out THAT OFTEN (buds - not ears). Volume adjustment is rubbish - big, obstructing and ugly. Sound is still good though....