I've had a pair of these for about nine months or so now. At the time I bought them (not from here I might add) they were around £35.00. I've always like Sennheiser and I bought them knowing that they were likely to at least sound okay.
I bought them to use with my MP3 player. Normal earphones that come with MP3s, the in-ear kind almost always sound rubbish. My wife's Nano 'phones are terrible. She plugged the Sennheisers in and couldn't believe the difference.
The bass extension on these is outrageous. Try listening to Machine Head's Imperium, or Pantera or Slipknot and you will understand just how articulate these headphones are at delivering weapons grade bass response as well as articulating crisp higher frequencies.
The only minor downside is that because they are open backed other people will hear a bit more of what you are listening to. But if that doesn't worry you overmuch since most ipod earphones are about as noisy, I would suggest you are selfish and get these divine portable 'phones.
They fold up well and sound great. They are also comfortable to wear and don't fall out your ears.
And they kick some serious [...] on sound delivery.