I find them slightly uncomfortable and find the treble to be mediocre. The bass is excellent, but I still don't like them. I liked the rubber buds that they use, but none of them seem to be the right size for me, so they are either uncomfortable or fall out easily.
The only canalphones I've ever liked were Etymotic ER6i, but they're way too flimsy. I bought a pair with a broken cable, but they didn't survive another trip through the wash. But the thin flexible cable reduces the 'microphonics' issue I mentioned earlier.
What I really want is headphones that sound like speakers. So when I mix, the levels don't sound completely wrong on speakers.