Pros: overall design (pads, comfort, looks), build quality
Cons: non-audiophile sound, mediocre (detachable) cable
From what I understand about the P5 headphones, they were not designed with the audiophile in mind. There are two "versions" of the P5: the first with the untrimmed foam earpads and the second with the trimmed foam earpads. The second had improved clarity across the range by removing the foam that blocked part of the earpad canal.
I purchased this headphone as a durable, stylish, portable, and isolating headphone to use across the streets and such. The design and durability is what caught my attention. I have enough audiophile-oriented headphones and few are portable. The "portable" closed backs are not of durable build quality, are very uncomfortable, do not isolate enough, and look ugly. They do however sound fantastic and are excellent bang for the buck.
I purchased the P5 "second version" for $300 at a nearby Apple store. I was prepared for extreme aural disappointment.
Metal and leather, no plastic in sight or any weak spots. The build quality is superb throughout the headphone and it can probably last a long time even when manhandled. No loose parts, finishing is superb, very solidly built. This is the type of quality I expect from $300 headphones, full-sized or not. I do not get enough of this quality from the other plasticky headphones I have, even the "studio monitors."
The cable is sorely disappointing. It feels very cheap and thin, even is detachable.
The foam earpads are very soft and smooth. This is the second most comfortable "real" headphone I have ever worn. The headband is well padded and the headphone was designed to fit on a human, not a rock, a rhino, an elephant, or a unicorn-monkey-horse. I can wear this for hours at a time and the only discomfort would probably from when my ears get hot from the leather (not too bad). Very comfortable.
First off, the isolation from the earpads is black-magic superb. A seal is achieved but it also causes the driver to flex when put on. The driver-flex that makes a slight popping noise is annoying sometimes. Isolation is superb to my HD25s and matches that of my cheaper IEMs such as the Brainwavz M2 earbuds. However, at times it can put pressure on the ears.
The sound is....relaxed, rolled off, no sibilance at all or any sort of harshness, maintains good level of definition and clarity, absolutely no detail for cymbals (e.g. jazz-ride rivet or chain sizzles sound dull), lower-highs well articulated and clear with medium level of detail, smooth texture. The mids seem delicately pushed , showing signs of slightly bloated lower-mids; upper-mids have oddly good detail, vocals sound superb but give Bieber an extra testicle due to the slight bloating
Upper bass has little punch, smooth texture, "lush" feeling - little impact but lots of body (not one-note bass by the way), making it sound very slow and draggy but in a pleasing and buttery smooth way
Lower bass is accentuated, giving the headphones a "sub-bass" feel - almost like a very cheap subwoofer that you would find in a shoddy example of a ricer car. However it is impressive at the low hertz, at least compared to other headphones in the price category
Soundstage, as expected, is very narrow, very pushed together but with strangely good depth. Not sure why. Overall very very smooth, like a cup of rich hot chocolate. Non-fatiguing, to say the least.
The P5 really does gets weird; this is one of the most odd sounding headphones I have heard. It is dark yet well defined and with detail pushed from strangest parts of the frequency spectrum, and detail pulled away from the strangest parts - at least compared to other headphones I have owned. It is mediocre to any audio enthusiast worth his salt.
But the P5 sounds oh-so-satisfying. I can't describe it.
The P5 gives a consumer-hi-fi oriented sound. What you would expect from Bowers and Wilkins. It's as if B&W was giving a sneak-peek at their 800 Diamond series but then putting mixing some mid-fi stuff in, if you have heard B&W stuff. Or a vintage JBL studio monitor (the larger loudspeaker rectangle monitors).
There is something I can't describe that makes it awesome. Still trying to figure it out.
This is my basic go-to portable for commute, and I enjoy it. I would completely understand if you would dislike it, but this is one of those "you have to use for the sound to sink in" headphones. At first, it sounded like any disgusting consumer headphone. But over a period of time, I realized that the driver is actually extremely well designed and through some research, I found out that the earpad was the main cause of the bloatedness or mudiness.
Overall, I have mixed feelings about the sound. But if I want some solid sound, I grab my full-sized pair of extreme-detail-retrieving, frequency-refining, extreme-critical-listening headphones. For what its worth, the P5 is the epitome of consumer-targeted design in a hi-fi presentation.