Read Consumer's Reports. I checked into VW's about 6 months ago, and CR said that the only "decent" VWs are the newest ones. Go any older than the ones that just rolled off the assembly line, and you're asking for trouble out the wazoo. The biggest problem is that the electrical system just kicks the bucket one day, and then you're screwed. The car will run, but with no gauges and no lights other than the headlights and taillights. A freind of mine has/had a 99 Jetta that the electrial went on in January of 2004, he was ******, to say the least. I would imagine the engine is decent, but the rest of these cars pretty much suck. The ride isn't the best, and the acceleration leaves something to be desired, unless you get the VR6 models. My girlfriend considered a diesel golf this past March, but rejected it after driving it in the cold. It had NO power until it warmed up, after about 15 minutes of driving.
FWIW, I find Consumer Reports to be a good source of information, along with talking to people who have had experience with what I am considering.