I own a DCT-equipped Focus and can tell you there's a ton of truth in these stories. Unlike VW, Ford uses a dry clutch, which seems to be the source of its problems.
When working properly, the DCT is actually pretty engaging: crisp shifts, sporty feel, great fuel economy and the like. It can get confused at times and produce the odd or rough shift, but these are not so common.
The problem is the DCT doesn't always work properly and can produce pronounced clutch chatter at launch, clutch slippage during acceleration, gear grinding, etc. Ford has updated the software many times, which has helped. Leaky seals were any issue for a few model years allowing transmission fluid to contaminate clutches, new seals have been introduced. And the transmission control module (an expensive bit that actually does the gear changes) is subject to early failure. Ford has extended the TCM warranty, but that won't help much when you're stuck somewhere you don't want to be.
Despite all of the this, the DCT is still a mess. Mine is in for its second clutch replacement (in 35,000 miles) despite revised seals and up-to-date software. The current theory seems to be the clutches warp, creating chatter and slippage.
I can't believe the DCT will survive into the next generation Focus. So, if you want a temperamental, unreliable, soon-to-be-orphaned piece of hardware that shouldn't be owned outside of warranty, this is the car for you. Otherwise look elsewhere. If the Focus appeals to you, go for a manual of the 1.0 EcoBoost, which is available with a conventional 6 speed automatic.
As a short answer to your question, there is no transmission available in North America that is more troublesome. And second place isn't even close.
