Pros: Very comfortable and secure, great isolation
Cons: Tinny sound, with false, pumped-up bass
Before these, I had the Etymotic ER6's and the Ultimate Ears TripleFi. I'll be comparing the Klipschs to these.
First off, let me explain quickly why I bought these. I lost my TripleFis and frankly just wanted a pair of headphones quickly and cheaply. I had been curious about the Klipsch product and when I found these for $30 on Amazon with free 2-day shipping, I jumped: that's impulse-buy prices.
The sound quality on these is great for $30. But if you're going to compare it to either the Etymotics or the Ultimate Ears...well then you have a problem. The Klipschs are loud enough and have good bass output, unlike the Etymotics, and they aren't boomy or bass-heavy. But they sound fake. The bass feels thin and loud, rather than full, the mids are OK, and the trebles are terrible. The treble is hissy (I'm talking cringe-on-each-cymbal-hit hissy) and annoying. They can't compare favorably in any way against the Ultimate Ears. Don't get me wrong, they sound far, far, far better than stock earbuds, but you can definitely tell the difference between them and better buds.
But it's not all bad with the Klipschs. They just as comfortable as the Etymotics and provide about as much isolation, they also stay secure during runs. Compared with the Ultimate Ears, these are a joy to live with on a day-to-day, which I found extremely uncomfortable in comparison and actually much worse at noise isolation.
One additional comment: these are meant to be worn either traditionally, or with the wire coming up and around the back of the ear like some sport and high-end earphones. Unlike the latter however, they don't have the rigid wire just below the earbuds that helps keep them in place against your ear when worn like this. Unfortunately (or fortunately?), the Klipschs sound significantly better for me when I wear them this way because they are able to go just a tiny bit deeper into my ear. It's a little annoying having the non-rigid wire flop around behind my ear; not a dealbreaker.
Some of the reviews I read claimed that for the MSRP of $50, you're better off getting an $80 pair like the Klipsch Image S4s, or my recommendation, the Etymotic ER6s. I agree wholeheartedly; the sound quality difference is totally worth the extra $20-40. In my case, I bought these for $30 and at that price, I say they're very respectable; that's a low-enough price that I don't care if these break or are lost in a year. Just don't expect sound quality that will blow you away, unless you're migrating straight from those cruddy Apple earbuds.