My current Golf hasn't have any problems really apart from the bonnet sitting slightly out of line. The mechanic opened it, and twisted it a little. Fits perfectly now.
My previous Golf ED30 however....
On the second day of ownership, the passenger door deadlocked itself! They kept the car for almost 2 weeks and gave me a Polo whilst they fixed it. Whilst fixing it, they totally wrecked the inner door card. I got the car back, but had to wait another 2 weeks for a new door card. They also swapped over the front grill as it had a massive scratch on it from new too.
Other than that - I had no problems for the 20 months ownership until some tw@t ran into me and wrote it off!