Don't own one, but picked up loads(I work for a recovery company). I've also signed several bill for replacing the damn things on late '90s LT vans.
It shows up worst when the car won't start due to a duff starter motor. You have that replaced, and 6 months(ish) later, the same thing happens again. So now you're looking at another starter, plus a clutch and the DMF itself. That's a four figure bill. It's so common that the local starter specialist won't guarantee a TDCI starter unless there's a bill for a new flywheel at the same time.
DMFs are a stupid idea, badly implemented. Failures are common in pretty much everything that uses them. Which is why conversion kits are so readily available, from an Avensis to Porsches. Interestingly, it's supposed to be impossible to tell the difference just by driving the car.
I used to think I'd prefer a diesel if buying a new car, but what I see now makes me seriously reconsider that. Ever watched someone try and get the injectors out of a Trafic engine? You have to remove the engine, make a puller( astout length of bar with a stop welded on one end and a large weight from the gym) and hope you don't wreck the head in the process! When there are common turbo, injector, fuel pump and sensor failures, most of which cost more to fix than any car I've ever bought, I don't want to get involved.