Pros: sound quality, durability, isolation
Cons: price, comfort
I bought them as an upgrade for HD-215. I needed better isolating headphones because of the noisy environment. I was trying several models (Technics, Pioneer, AIAIAI,...) and I loved these the most. Sound quality is #1 reason for me. They might be not the best looker but I use them as all-round headphones while commuting, DJ-ing, at studio or at home. The only downside I found so far is they are little bit uncomfortable when wearing for a longer period of time, especially together with glasses.