Pros: Very balanced sound, great sound stage
Cons: Price - but you get what you pay for :) difficult to drive without proper amplification
I had the HD 555's previously and I wanted an upgrade. Had been very happy with Sennheiser so I decided to stick with them. These were a very noticeable upgrade of my previous set and they were totally worth it. Make sure you have a good amp for these though otherwise you can never truely appreciate them, as well as a good source.