I have the K702's and after 400 hours of burn in they are a wonderful sounding headphone to me. They are very detailed, their soundstage is one of the best I have heard in a headphone. The midrange I feel is balanced with the rest of the sound, I don't find vocals to be to forward or recessed from the rest of the music. I feel they have a very balanced sound. The bass is what you may read about being their biggest complaint. They have bass it is very detailed tight and seems to have good accuracy but all I have to compare to are the HD650's I previously owned and my home stereo. The bass however doesn't have the impact of say the HD650's or anywhere near the impact that I get when listening to my stereo, but it is not disappointing by any means.
I find the K702's give you a very accurate presentation of the recording you are listening to, if you give them garbage you will get garbage, if you give them a masterpiece you will get a masterpiece.
Now keep in mind these are my impressions after 400 hours of burn in. These headphones do need extensive burn in, so if you do buy a pair new they did tend to sound a bit bright and thin when I first got them and the soundstage wasn't as open and airy as it is now. So don't give up on them too quick. Also a good amp will help and is the are I need to improve on next. I am driving them with my Apogee Duet right now which I feel is doing a decent job but I know I can do better.
Hope this helps and good luck with your search.