I have finally pulled a plug on those as a gift to the kid. He mostly listens to hiphop, punk core and electronics and spends a lot of time in Moscow subway (a hell of a sonically aggressive place) on his daily commute to college. He also claims he can't stand IEMs.
Since there is no local store where I could audition the Beats I have read almost half of the 30-page thread here before placing a bet on ebay.
I spent full two hours with the cans listening to the music I know well and to some less familiar tracks both from iPod and Corda Move hooked to USB of Mac Pro desktop. I tried to compare the Beats to some phones I own of the same or lower price range - RS-325i, PK-1, ER-4S and K601 - all of them very different and representing various approaches to sound. I also threw in a pair of ES7 - the phones I dislike, but the only classic closed backs in the household.
My verdict in a nutshell - the Beats are plainly very bad headphones.
First, they hiss. The active NC circuitry is always on and when you put them on first thing you hear is the hiss. It's not loud at all, but well-spread across the spectrum and quite annoying. More about it later.
Second, they leak badly. They're super-closed on the inside, so to speak, the sensation emphasized by active NC, and absolutely open on the outside. Possible problem with listening to offensive lyrics in a public place.
Third, they just sound bad. One of the simplest tests I always run on a pair of headphones is comparing a fragment of a chamber piece played with catgut and synthetic strings. Usually, the difference is clear. With the Beats any violin sounds amplified, no difference of string material is heard. There is no instrument separation in a string quartet, not speaking of a symphony orchestra. Mixed choir sounds mashed, with no group separation (Grado is able to discern individual voices). Even in rap music, the complex layering in, say, a song by Antipop Consortium is completely lost. I attribute this to above-mentioned hiss, which eliminates a lot of higher-harmonic information responsible for timbral differences.
Fourth, they really do isolate.
Sorry for long post.