As far as extras go, you don't get much. There's no inline remote/microphone for making cell phone calls. And the carrying "case" is just a thin cloth pouch that doesn't serve much purpose other than to cover the headphones and keep them from getting scratched up if you stow them in a bag with other objects.
For $30 headphones, I thought the f38s sounded quite decent, though they fall just short of being special for their price level. They offer a good amount of clarity and bass, though they're a little aggressive-sounding and a bit pushy in the midrange. I compared them with Panasonic's RP-HTX7 headphones, another budget-priced over-the-ear pair that also retails online for around $30. I thought the Panasonics were a little fuller-sounding and slightly more detailed, which is why they're rated at four stars. That said, the f38s performed well with a variety of music. They're fairly dynamic and have some punch to them, they're just not the smoothest, cleanest-sounding headphones. That's not surprising, considering their price point.
I'm always on the lookout for headphones that give decent value and the Incipio f38s certainly fit the bill. For $30 headphones they offer quite respectable sound, and I think the majority of people who put them on will be impressed by their comfort level and build quality. Overall, as far as sound quality goes, the f38s aren't quite as good as the Panasonic RP-HTX7s. I also thought the $13 JVC Flats offer about the same sound quality in a more compact package. However, the f38s are more durable.
While they may not be the steal the JVC Flats are, the f38s are very solid headphones for the money and will be going on our list of best headphones for less than $50.