I've had mine for about 3 years now and I'm still very impressed with them. As they break-in, they will continue to improve.
You might think about a replacement cord, nothing exotic and not for any sonic improvement, but the stock cord is awfully flimsy. There is about a $28 replacement available at Amazon which is much more substantial. I only learned of it after mine developed a short. The downside is that the replacement I got does not have the nifty 1/8" to 1/4" deal that the stock one had, it's a straight up 1/4" plug.
I originally got mine for late-night listening to my main stereo, but now I use them for everything -- from my most humble sources (laptop phone jack, ipods) to better stuff, and they always sound fantastic -- obviously much better with better sources -- and are insanely comfortable. I did draw the line after wearing them on the treadmill a few times, as that seemed a bit reckless.
They are indeed great cans.