Pros: Tight, punchy bass. Clarity. Sensitive. Resist distortion.
Cons: Limited soundstage. Cable doesn't detach.
Anyway this review is about the MDR V55s and I like them. My source is Spotify Premium set to "Extreme Quality" via a Samsung Galaxy Note 2. Recently I added a FiiO E07k Andes amp which gave increased volume and beefed up the bottom end. Mids and treble seemed to gain extra authority too. I've had to be a bit careful as I like it loud and with the amp these cans will go very loud without distorting. As do the less sensitive Logitech UE6000 'phones I just got for NZD $138 via Amazon. I've been running the Ultimate Ears in for a few days and can safely say the Sony's have them beat down low. Basslines and drums go lower, hit harder and the bass is tighter. Very impressive. The UE6000s produce more bass in terms of quantity once you switch on the noise cancellation, but the quality still lags behind the Sonys. On certain bass heavy tracks the UE6000 earcups will actually vibrate or resonate which I do enjoy so I guess I'm a basshead.
Moving on up the midrange performance is similar with the Sonys getting closer to the music (too close on poor recordings) while the UE6000s are buttery smooth, non fatiguing and have a much wider soundstage. Perhaps a touch more detail too while the Sonys can exhibit a hint of grain.
With regard to treble the Logitechs are smoother if rolled off and the Sonys have more sparkle which can be a bit bright over time.
Of course the build quality of the larger over ear 'phones is better, they look better and they are more comfy. The on ear MDR V55s can get a little uncomfortable after 30 minutes or so.
Overall I think the Sony MDR V55 cans are a bargain.