Pros: great sound
Also another owner here for whom the ATH-A900 is the first pair of good headphones.
They definitely stand out with their styling and massive aluminium cups. I just dig circumaural headphones. They're just so much more comfortable that on-ears.
Love the sound which works well for my taste in music (electronic/rock) and for use on PC watching movies, etc. The bass is good, but their is something lacking in the midrange. Nothing a EQ change won't sort out. I have run these through a C&C XO amp fed from ipod line-out with no EQ change on the ipod and they sound good. They can take a good whack of power (if you're into going deaf) without distorting in any way. Massive drivers on these.
The ear pads are comfortable but I'd suggest trying out the leather pads as these leatherettes wear out fast. However, I cannot get used to the "headband" and have on several occassions had bad thoughts on how to rip the headband off and try to graft on something more conventional. I must have weird hair or something, but after a while of having these on my folicles hurt. :D And they'll make you look pretty weird if you've got a small head. :D I don't have a small head, but it's not a large enough head I think. :D The band can be rattly too and they don't feel that secure should you not want to be sitting upright while using them.
They are durable headphones though and still pretty good value for an all-rounder.