Depends what engine you have in the C30, and mostly on the type of journeys the car does.

However, I've had two DPF-equipped cars (a Mondeo and now a Volvo V60) for a total of 5 years and nearly 60,000 miles, and had zero DPF problems. This is despite my daily commute being 3.5 miles to work, and 3.5 miles back home. Some people would have you believe that this kind of use would block up the DPF in a week, or cause it to melt down like Three Mile Island.

The 1.6 C30s do seem to suffer from the odd engine mapping problem according to the Volvo forums but there is an ECU update for this.