Pros: Price, SQ, Price, Clarity, Price
If there are better sounding headphones in this bracket, they sure aren't available to the public yet! The KSC75s just might represent the apex before the downslope of diminishing returns.
The sound: Very fun and engaging all-purpose sound. The bass is certainly present, although far from basshead territory, the mids are maybe a little recessed, but they sound just great all the same, and the treble extends nicely without a trace of sibilance or harshness.
Design: Probably the only downside to these guys. The driver covers look super-cheap and the earclips make these the most uncomfortable cans I've ever used. Granted they do get more comfortable as they loosen up. I however, would recommend to anyone who experiences discomfort (which will most likely be anyone with ears) buying a partsexpress headband to use with the 75s. Super easy to install and totally relieves all of the discomfort.
Value: Like I even need to go here. For under $20 you can purchase earphones that rival in sound quality, IEMs and on-ears in the $75-$150 range. When's the last time you saw a frequency response of 15-25k Hz for phones that cost less than $100 brand new!? Such a great deal! At the very least everybody should try these just once. I was able to pick up mine for $5 a pair as they were recently put on clearance at a local office supply store! Two pairs of $100 sound earphones for $11 including tax.
It should be mentioned that the 75s don't come with any accessories like 1/4" adapter or case, but honestly if you need a case, you can find something cheap.
If you need some beaters that are gym-ready, office-ready, or just walk-around ready, look no further. Plus they won't break the bank! Kudos to Koss!