I have had my Nokon cables for over 18 months now, and I couldn't be happier with the set-up! When I first started using them, I noticed how smoother the shifting was, compared to conventional housing, and it's still good to this day. Braking performance is very good, I found that I could modulate the brakes abit easier with the Nokons, than I could with my previous Campy housing, however that's just my POV!
Even to this day shifting is excellent, I'm still using the original cables, and I see no need to change them out, after over 20,000Km.of riding.
They are abit pricey, but they have far outlasted previous conventional cables/housing, that I have used, and changed over in the past! In time they will pay for themselves!
Installing them on the bike is a PITA, according to the LBS, but once all set up, you will notice a positive difference in shifting/braking.
Oh, and they do add to your bike's appearance as well!