There are a lot of problems with them, most are pretty well documented by now. The early first gen 3.5L EBs are the ones that stretch the timing chains. They upgraded the chains sometime between 13-14 and it's really not an issue anymore. There is a TSB out for a whole bunch of the 2.7Ls that had bad valve guides, they come in with a multitude of symptoms, usually no oil pressure due to excessive consumption is the most common. Some of them wind up with new heads, others get a new long block. The intake coking is well documented and it happens with virtually all of the EBs, there have been several revisions to try to address it but it still occurs fairly often.
The second gen EBs are highly revised, even the blocks are slightly different, but they still aren't as reliable or refined as the 5.0L IMO. A lot of these issues are things Ford should've caught during R&D. I dont like how they are using their customers as guinea pigs. I get it that unforseen stuff happens with all cars, but I think Ford was rushing to get to market with these and spent a lot less time on the engineering than they should have.