What's not to like?The X5s are superb phones, although whether they kill giants, I can't say.
When I first got them, they did sound a bit thin. Whether through burn-in (not really a big believer in that) or (more likely) experimenting with the different tips, the sound soon became full bodied.
Highs and mids are wonderful, the female vocals and piano music that I favor rate very high, and for those wondering about comparisons with the X10, the bass is plentiful.
I've tried them with and without amplification, and they sound fine connected straight to my iPod Classic.
I've had a set since last summer that I use for daily train commutes and can report no problems at all, including the cord issues that a very few X10 owners have had.
In short, sound is top-notch, reliability is excellent, and comfort, as others confirm, is at the top of the heap.
What's not to like?
Comfort is so good, that I don't want to risk being without the X5s; I bought a second pair during the sale.
Would I pay full price again? If I had to, absolutely.
But check around and you can usually get a better deal.
Hope this helps.