I've seen a lot of conflicting information on these, and wan't to give my perspective:
The sound quality depends entirely on the fit, if the eartips make a good seal with the stem, ie need at least a day to reform to the stem once put on, and they fit your ears properly, the sound is detailed, neutral with little but still noticeable bass. I'd recomend you try them on with the tips on them already, and if they fit fine, DO NOT take them off. my input so far on the sound was with the standard size foam tips preinstalled. After I fiddled round with some of the other tips, I found only those ones fit, and putting them back on again meant they fit very loosely on the stem, and gave a tinny unpleasent sound which is probably worse than even the cheapest phone earbuds.
Because of that, I simply put them in the case and left them for a few days, when I though to have another listen, I found the foam had made a good tight fit with the stem, and the sound, was back to the sound I initially heard, and frankly, very impressive, although there wasn't much bass, the neutral and detailed sound made them enjoyable at very very low volumes, because of so much detail, I mean at 20-25% from a phone.
Simply put, if the tips fit your ears, and do not get completely destroyed by taking them off or anything else, they sound great, but if the tips don't fit the stem of the iem's properly, you will get a very tinny cardboard sound.