When gas went up to $1.75 a gallon in July '01, I purchased the Jetta GLS TDI. I got great gas milage right off the lot. I averaged in the first two years 32,000 miles. After five and a half years, I have over 129,000 miles. Over the lifespan I have averaged 49 - 52 mpg. If the maintenance is kept up and it is driven as any diesel should, long trips, you shouldn't have too many issues.
Cruise control, leather interior, Monsoon sound system, the torque to climb hills without requesting more fuel, are all priceless.
The cup holders should not be above the radio. It needs a better lower engine cover. The tail lamps should last more than twelve months.