There have been reports of people being almost stranded because the software controlling the DCT gets confused. Usually, a redraft seems to cure the issue. Of course, there are many stories about bad DCT behavior, but these are annoying rather than debilitating.
The good news is that the DCT itself should be as reliable as a typical manual gearbox, provided the clutch behaves. It doesn't have a torque converter to heat up the fluid, so none of the worries that attach to that in mountain or city driving. The clutch itself is a different issue: hard to say how long they will last.