I've had these for 2 1/2 years now, and have been very happy.  They replaced my Sennheiser 570, which are also very good, but not as clear as these.  The AD700 is also better than the low-end Stax that I used to use.  I'm driving them through an older Arcam 45-watt integrated amp with no problems - volume control is barely above the minimum for a decent listening level.
 
Dynamics and imaging are very good.  Bass is normal, not overemphasized.
 
Issues: They're crazy big, even on a medium-sized head.  Therefore, they move around a little, but they are still above-average in comfort.  I'd prefer it if the wings were more adjustable.  Being open-backed, they leak a fair amount when played loud.
 
They also can sizzle a bit on certain high-frequency sounds or sibilant vocals.  I used to think that it was mistracking by my Ortofon 2M Bronze, since I mostly heard it on vinyl, but I eventually noticed that the same recordings behave better when played through my B+W speakers.  For 95% of my records, this isn't a problem, but for a few that are cut really hot on the high end, there's some breakup.
 
These are still worth considering at current prices.  However, I would not use them to drive a portable device without a headphone amp.