I had an early Mk5 GT TDI 140 manual. (Jan 04) Positives were good midrange, effortless 90mph cruising, averaged 47mpg over 35k miles, great load lugger, motorcycle tower, and did 2 family holidays, 4 up, 3 mountain bikes, on hitch mounted rack, and a large roof box, still sat at 100mph on the autoroute and never dropped below 40mpg.
The negitives, were horrendous reliability, 45 days off road in 30 months, and one massive row with VAG UK Customer dis-service dept. List of replaced parts too long to list, including a gearbox. Also the car had a real tendency to bottom out if pushing on over undulating roads,
to the point where I ripped off the engine undertray on one fast B road. The dampers could not cope with fast changes in compression/uncompression scenarios.
Took a leap off faith in VW (and some VAG cash) to replace it with a GTI, and to be honest it doesn't even feel like you are driving the same model.
Think I had a Freitag car, but the early ones were definately suspect build quality, as I knew other owners with similar stories.