I thought I would share my first impressions and experience with this headphone. :) I will only concentrate on the sound part, since everyone knows how well built and comfortable they are (or can be... for me they are really comfortable).
First off, let me tell you that if you're expecting super audiophile grade quality, look elsewhere. My initial expectations may have been a little high myself especially since I'm used to listening to my home setup: Macbook Air > HRT MSII+ > Bellari HA540 > K702. This setup is just amazing and since this is my reference I can't lie... I was disappointed at first with the sound of the P3.
Initially I found the sound muffled and too warm, lacking in transparency and highs. I appreciate a warm sound, but this is quite warm with recessed treble. (BTW this is my university setup I am listening with: Macbook Air > HRT MSII+ > Bravo Audio V2 > P3. My even more portable setup will be the same, minus the Macbook and DAC to be replaced with a LOD and IPod.) But after listening a little more, I oddly started to appreciate the sound.. It's sweet and the vocals are amazing. The soundstage isn't the largest but for a headphone of this size it's pretty impressive. The 3D positioning of the instruments is even more impressive since I am able to pinpoint where the instruments are coming from on the space in front of me quite easily.
Despite the initial feel of a muffled sound, after about 30 minutes I realised that the sound is pretty clear and I am able to hear little details in the sound. The song that impressed me the most was Toni Braxton's "Un-Break My Heart (Album Version)" with it's clear highs which even sparkled with the P3. Also, Massive Attack's "Mezzanine" album sounded amazing with these phones... With their fast, punchy bass which extends well and liquid mids which are a treat. So of course compared to the K702 setup I always listen to at home the P3's are muffled and way too dark/warm. But forgetting about the reference and remembering what these headphones are for I can't complain! :)
So all-in-all, I am quite impressed with this headphone for my portable setup! The warm sound is so pleasant to listen to while relaxing or studying for your Process Modelling and Analysis final exam. ;)
I hope my little review of my first impressions of the Bowers & Wilkins P3 headphones is of some help to someone. I will post more information once I have enough time with the headphones if anything pops up.