I use them only on the 3hr bus ride to school. I use the flexi rubber part and they're very comfortable. If you google 'best headphones' in the #3 spot you'll see my friend joi ito talk with one of shure's engineers on his blog.
They are good portable headphones without a doubt. I love the isolation, it makes up for the lack of high frequency response a bit. I will eventually upgrade down the road but for now they are satisfactory and allow to me to enjoy my music in loud public places while still preserving my hearing.
Maybe not the "best" for the money but they were available locally for me here so I bought them because I couldn't take the Sennheiser MX400s anymore!
I love them! As others said they sound better amped but still arn't too bad directly out of the source.
Given the chance I would have liked a chance to hear the Ety ER6i but I think those are a bit more money than the E2Cs.
had them for 6 months, now I have e4c.
They are very good earphones for the price, the upgrade from earphones like sony ex71 to the e2c is one of the most enjoyable. I recomend them to all my friens that begin to pay attention to the sound quality.