I picked a pair of these up when my Sennheiser CX 400-IIs gave up the ghost after not even a year (they have since been speedily replaced by the Amazon Market vendors). At first, I wasn't too sure: they felt uncomfortable in my ear, and the upper registers felt harsh and jangly. But, after a period of settling in (I always wondered if this worked for earphones, and I'm now willing to believe it does)I absolutely love them. The sound is so good, so warm and clear and pure, that I'm picking up details I've never heard before, and -- like someone else who's posted a review -- I've gone back and am listening to almost all my music collection again just to hear the difference.
I'm not too sure how isolating they are, but that doesn't matter so much to me, and the fabric covering feels great and distinctive, but I'm not convinced that they prevent tangling. The true test for me is longevity: I've gone through a variety of Creative and Sennheiser earphones in a bewilderingly short space of time, and I'd love these to last (this is a lot of money for me, the most I've ever spent on earphones). Meanwhile, while I have my Sennheiser X400s back, they're relegated to spares and I'm sticking with the RHA! Buy these and give them a chance -- you won't be disappointed.
UPDATE: Last week, one of the earbud tips fell off, all my own fault. I looked on Amazon for spares but couldn't find any, then contacted RHA via their website to ask where I could buy some. They offered to send me a set, gratis, through the post, and these arrived just a couple of days later. What service! What support! Top marks, RHA.