I'm quite new to the hobby, having few experience with IEMs (owned 7 and heard a bit more than 10, most mid and low-fi), so maybe I can't provide the most detailed description, neither compare them to other top-tier IEMs.
Forgive any grammar errors, I'm pretty poor at writing. Forgive my lack of precision on describing sound too.
Most of my library is in MP3 320 Kbps or FLAC. My music preferences are mainly Electronic, Rock and Classical.
Unboxing and Accessories: Pretty simple, it came in a small box, opening it has a small plastic protection and below it are the earphones in the foam. It came with a pleather case, a small and 4 pairs of earpieces: 3 pairs of silicon (S,M,L) and one of foam.
Build Quality: These are perfect. Audio Technica used Titanium for the housing, and it not only looks good but also looks very resistant and the plastic part feels pretty solid and thick. There aren't strain relief on the earphone, but its well made on the connector. The cable is the best I saw in my life, neither thin nor thick, very flexible and almost-zero microphonics. Seems durable too. These can withstanding a bit of rough treatment, but I prefer to not try.
Comfort: Not too much to say about, these are a bit annoying when wearing straight down, but disappear completely when worn over-the-ear.
Bass: Have an adequate quantity, but amazing quality. Well defined and textured (but not textured as CK10), punchy, very controlled, fast, the bass of this earphone is fantastic! Don't extend a lot, roll-off gently past 80 Hz, becoming inaudible on the lowest of the lows. Perfect for Electronic music, not so great with Rock and Metal, also good for Classical.
Mids: The best part of this earphone. Rich, defined, detailed, great decay, lush, the mids are just perfect. There is a little emphasis on upper mids that make things sound more lively, bringing a bit of aggressiveness, but still very pleasant sounding.
Highs: These seem to be quite extended, airy and refined. Never piercing or harsh sounding, highs are smooth and clear too.
Soundstage: Good size for an IEM, seems natural, imaging is good as I hear instrument being well placed. Instrument separation is good too, I can focus on one instrument without problems.
Resolution: High resolution, even higher than CK10, but don't show the details in your face like the CK10. Detail is present but is more subtle. Shows excellent transparency and doesn't sound congested in complex passages.
Amping: Using an amp brings noticeable improvements, especially on bass. It tighens the bass and add a good amount of impact, mids become more detailed and highs are more present. These phones have a good amount of "reserve", you feed them with a cleaner and more powerful source and they react a lot better. Not a must, but if you want to extract the maximum from them, then you will need an amp.
They are quite picky with sources, sounding rich with good, warm sources.
Conclusion: Although expensive, these are great IEMs, having the best build quality and great sound, in fact, the best IEM I heard. I highly recommend them, even with the serious lack of accessories.
UPDATE 10/08/11: Added Amping.
EDIT: Just adding a pic.
Edited by KevinWolf - 2/6/12 at 8:44am