Pros: Great sound, inexpensive, lightweight, open ear, retro looks.
Cons: A bit fragile.
I'm on my third pair of PortaPros over the last 12 years. My last two units have either suffered a rattle that eventually became irreparable or something terrible happened to them (left in a car seat in the sun, crushed by a contractor's pelican case).
I never question buying them again, though, because I love the sound so much and they're so damn cheap! In my opinion they rival all the headphones in their class (including the Senn PX100's which I also own) and many larger 'phones. They have a depth and clarity that I really enjoy listening to, and the open design means that I can still hear everything around me while I have music playing, which makes them perfect for the office or walking city streets (where I still want to hear what's going on around me).
Love these things!