I had a set that I bought at the end of last year, had the K3 coating on it. Here's my quick and dirty review:
The Good - Look really cool, especially under a black light. Sound great. They have that bright attack and clarity you'd expect from new DR strings. Classic round-wound grind.
The Bad - Coating chips away with pick use. It wasn't horrible, but up close you could see where the chips were. What was more noticeable was the build up of finger gunk, there's just no hiding it on Neon Orange strings. The coating is not comfortable to play IMO. I do a lot of slides up and down the neck, and the first one hurt like a %$#@. It got better as I played them more, but if you slide aggressively your fingers will have a little chat with you.
Overall - Fun strings that sound good. I got them with a gift card I had laying around just to see what they were like, but I personally won't buy another set. The burning sensation they gave my fingers were the deal-breaker for me.
Hope that helps!