Lots and lots of conversation on this topic. Has Ford done a lot with the DCT? Yes they have: updated software (many times), revised clutches (up to version "F"), revised seals and a dealer network that may finally understand what they're servicing. So the 2014s should be loads better than early 2012s.
But. In my opinion, despite all of this, you are far more likely to have transmission issues with a 2014 DCT Focus than with any competing model. Now the odds are likely good it will be trouble-free, but it's still a bigger risk than a Civic, Corolla, Mazda3, Cruze, etc. The Focus has real strengths, but the DCT is not among them. And be aware Ford is actively considering a CVT alternative for its next-generation small cars, which tells you something.
Please be advised that the Mazda 3 and the Cruze uses a conventional automatic. The Civic and Corolla uses a CVT. In almost every review I've watched on youtube regarding these cars, the consensus is that the Civic and Corolla are competent, reliable cars, but are not fun to drive (but that is not their target audience. People who buy Civics or Corollas don't care about a sporty ride). The Cruze is also considered a competent car, but maybe not as reliable as the Civic or Corolla. Most reviewers gush over the Mazda 3. I've driven the 3 and it is a very competent car, but is far more expensive than the Focus, on average.
The Focus is not a top seller in the compact car market, the Civic and Corolla will remaining the number one and two cars in this category. That being said, the Focus has consistently sold approximately 200,000 cars or more per year for some time now. No one has exact numbers, but to the extent that some cars are built with DCT issues, they are definitely a small percentage of cars sold. The odds are that if you purchase a Focus, the chance that it will be a defective car should be low. One final thing. In my opinion, if your car does experience the symptoms of a defective car, it will matter where you take the car in for the repair; not all mechanics are created equal.
Finally, it is true that Ford is considering using a CVT transmission in the future. My guess is that Ford is considering the switch because the dry dual clutch transmission currently being used on the Focus and Fiesta will no longer be produced after 2021 and Ford concluded that using the wet clutch transmission that will replace the dry clutch will be too expensive to use on their line of compact economy cars (that's just my guess, I have no proof). Be advised, however, that the 2015 Focus, from what I understand, will still be using the DCT transmission and my guess is that 2017-2018 version will probably use the DCT to coincide with the production schedule until 2021. In order to maintain their fuel economy goals, I think Ford believes the CVT transmission will be a smart, cheap alternative since a dry dual clutch won't be produced by Getrag. Even though Ford is working on an 8-10 speed transmission, my guess is also that that tranny will make it in their larger sized car, but not their smaller cars. Also, from what I've read so far, these types of transmissions have not delivered yet on high fuel economy goals thus far.
In conclusion, when working properly, the DCT is a great tranny that gives the Focus a nice sporty ride while providing great fuel economy. Good luck on your research.