I've had PortaPro for over 10 years.

Design-wise, it's far from the most beautiful headphone out there - the plastic looks cheap and the blue color is straight out of walkman age (regret not getting the_anniversary_edition). I never had to use the "comfort_zone" switch that controls the tension of the earpad (and transfers it to the temple instead), but I think just the temple pad helps a lot to make it very comfortable to use. Metal band is a very simple solution to making a reliable adjustable headband, but I should warn that adjusting it too much on your head is asking for trouble, as it tends to catch hair. I think I've replaced the ear and temple on the fifth year (the price of the replacement is very reasonable). While it looks cheaply made at first, it is surprisingly sturdy - as I've mentioned before, it gave me a decade of trouble-free operation through heavy use.

If there is one thing that bothers me, it is the vestigial feature of metal screw where the mic boom is supposed to bolt on. I have never seen a mic boom that will fit on this headphone, so it's very useless to have one (other than providing tactile indication of Left/Right orientation). Of course, there was an announcement at CES that a phone-compatible version of PortaPro is coming out, which includes mic and audio control, so that could potentially satisfy my wish to use this as a headset at home.

Good competitor for PortaPro is Sennheiser PX-100. I bought one around the same as PortaPro, and I also use it to this day. While PX-100 has excellent folding design and just as durable, I found that the sound to be less vibrant than PortaPro. Also, while PX-100 is better looking than PortaPro, it lacks the retro charm that PortaPro provides. On a more practical side, PX-100 lacks the temple support and is less comfortable to have on for a long time. Also, the replacement earpad for PX-100 is more expensive than PortaPro, as well as the fact that the cloth/foam cushions on the headband is not replaceable and will be almost useless and really dirty after a while, whereas all foams on PortaPro are replaceable and cheap.

Koss made the right decision not changing the original design of PortaPro: not only does it save them R&D costs, looking at their other offerings gives me the impression that this was a design miracle for them (e.g., the hideous Sports edition). Because it is so easy and cheap to repair and replace, this headphone get daily use. The ugliness makes the headphone stand out and people who knows a thing or two about headphones recognizes it instantly. I highly recommend this to pretty much anyone as the basic headphone to have - I hope Koss keeps producing this classic headphone for many decades to come.