Pros: Price, surprisingly neutral and accurate, not muffled
Cons: Not enough isolation to my liking, you will mistreat them just because they're cheap
I'm absolutely amazed at the price of these, with a fancier/heavier enclosure and more isolation these would feel like formidable audiophile universal IEM. Right now they punch way above their weight, both figuratively and literally. They aren't prone to hissing, and I haven't heard severe frequency response deviations with multiple sources, including straight off an integrated sound card, several smartphones, Sansa Clip Zip etc. Very easy to drive.
I've destroyed several pairs of these by accident just because 9.90€ earbuds are so easy to use carelessly. My only minor complaint is the way how buds tend to slip out of my ear, but that's the fault of my ear, not buds.