I avoided in-ear headphones for a long time for a couple of reasons. First, I always found them very uncomfortable as I have sensitive ear canals. Second, I didn't care for their sound reproduction as they tend to be too tinny, generally lousy in the highs, and flat as a board in the lows. I am probably a bit more picky about it than most, but I just want my music to sound good.
But I went through probably 4 or 5 different sets of headphones before I came to these. I am extremely pleased with these. The highs are very crisp, and the lows strong. In fact, I was shocked when I heard these, because I had pretty much given up on finding a set of in-ear phones that had any bass at all.
Keep in mind, it comes with three sets of inserts, so it is important you figure out which ones fit your ears best. Otherwise, you won't get a good seal in your ear, and the bass will be non-existant. A bad fit will also effectively eliminate the isolating quality of these phones. And like any other headphone that goes in your ear, you'll have to find the right placement. In my case, putting them in too deep kills the bass. But it's not a big deal, and you usually find the right spot within minutes of trying them.
The cord is braided, which is a bit of a double edged sword. It's more durable, and doesn't tangle as easily as normal cords. On the hand, they do make a lot of noise when they move around. So these might not make the best phones for working out in. Fortunately, there is a slider you can use to tighten up the two cords around your neck, which pretty much takes care of the noise.
I would definately recommend these to anyone. They may seem a bit pricy, especially when you consider all the sub-twenty dollars sets out there. But these are definately worth it. I've been through a lot of different sets of in-ear, and these are far better than any I've heard yet. These even beat out a lot of the over-ear sets I've had. All in all, I'm extremely happy with these.