From what I have read there were some early issues with the 6.7 but they were resolved rather quickly. This is Fords own design and built engine, and they are bettin the farm on it. Don't know anyone personally that has one, but posts on the net, folks are very happy with them.
Diesel Power magazine has an article about their 2nd version of it for 2015. Gonna lead the show with 440hp and 860lbs tq. That's a LOT of power. All this power even with all the emissions crap on them.
Speaking of emissions, I also read GM has just gotten a patent on an electric powered DPF that will eliminate the need for DEF. Time will tell on that one. I didn't think DEF had a long future. It hurts the REAL fuel mileage numbers too much.