Pros: Extremely comfortable, great sound, unique style.
Cons: Not very portable.
The A900s are my first set of headphones that I spent more than $20 on, so I don't really have much to compare them to. They sound great and are very comfortable. it's like wearing a big pillow of sound on your head. I've worn them almost every day for the last 3 and a half years and the show no signs of wear or damage (aside from the little scuff on the side from dropping them on a concrete floor).
Some people may not like the huge ear cups, and strange looking head band design, but I love it. Not only does it make them extremely comfortable, but it makes them stand out when compared to other headphone designs. If you like to take the road less traveled, these are the headphones for you.