Summary: Can't beat the price, worked extremely well... should consider buying if you need replacements for your mp3 player but don't want to drop a bunch of money.
Pros: Works great for 10 bucks.. really all I can say. Oh and they are Sennheiser.. ha. Better quality than the earbuds that came with my ipod nano... and WAY more comfortable. Wind up case is a bonus that works nicely for stuffing them in a backpack
Cons: None really, maybe the short cord? Worked perfectly for what I bought it for though (mp3 player).
Summary: For the price, you can't beat these! I find these fit in my ears similarly to the OEM iPod buds I used to have. This may be a plus or minus depending on the shape of your ears. I think they're very comfortable, and I put on the foam covers for an even more comfortable fit and better bass.
Pros: Great sound, fits well in my ears, comfortable. Cheap!
Cons: Cord reaches from my head to my waist with a few inches to spare. Not really a con for me but some may find the cord too short.