The new Fords with the 6.4 are awsome, let me tell ya, I have around 1500 miles under my belt driving my parents 08. As to the problems they have, here is what I will say. From the forums I read, there seems to be some problems, such as leaking radiators, and once in a blue moon an engine failuer. I have heard that the new Cummins 6.7 w/dpf was having some growing pains in the begging, and I was hearing people were going through turbo's every 5000 miles or so because of the regen system that dodge uses. They seem to be ironing out fairly well, and I think I heard of a couple engines giving in. The new duramax though, I have heard has leak tranny fluid in cold climats, but thats basically it, I havent heard of one giving up the ghost. But, there is somthing that I have to add. On these forums, it seems like the new Fords outnumber the new dodges a good 5:1, and outnumber the new chevies 10:1. This is for both the question and performance parts of the forums. I can see this driving around town to, the new Fords outnumber the chevies at least 10:1 around here, but I cant really tell the difference between the 6.7 and 5.9 cummins equiped trucks. So with that many trucks out there, and that amount of people on the forums, it makes sense you would see 10x the problems with the fords, because theres 10x as many people owning them and showing up on the forums than the chevies.
But thats just what I see.