Summary: A great choice if you are a fan of PX100. Bigger than PX100, but the sound is upgraded with higher clarity. A little less crisp over high pitch sounds compared to other closed-ear style headphones, but cannot complain with this price.
Pros: Know the Sennheiser name. Have them for home. Love the sound. Comfortable. Well made. Stable during wear. Good price, received addl off (limited time). Even without the addl off, the retail price in my opinion is fair. I would love to hear through a studio model, I'm sure I won't be disappointed ...
Cons: Do not fold, limited color (just black). But these things are easily sacrificed for the sound that Sennheiser provides.
Pros: These On-Ear headphones are far superior to the Bose OE2 for which reviews claim the fidelity comes up short on bass resonance. In comparing them to the Bose OE2, the HD 239's are superior across the whole audio range, and are significantly cheaper.
Summary: Being blind, my hearing is better developed than that of sighted people. It's therefore very easy to pick out impedance and a dirty sound in Hifi systems and headphones, so I'm rarely pleased by off the shelf audio products.