Are Volkswagen Jettas good cars?

Parts and repairs are cheaper for VW than almost any other car, because there are so many independent mechanics and parts makers.
It is only if you have to go to the dealer that they are expensive to maintain.
And if you do not maintain them, they will be even more expensive.
So find a reliable independent shop first, then ask them.
If you have to go to the dealer, then forget it.
For example, the timing belts should be done ever 100,000 miles.
An independent shop charges $250. The dealer wants $500. If you don't do it, the belt will slip, valves will bend, and you will have to pay $1500.
Great cars. Fun to drive, and last forever. I had over 350,000 miles on my GTI before the interior wore out and I sold it.