I haven't had any problems whatsoever, certainly not any electrical problems as some owners mentioned. The car performs best on the high octane gasoline though, otherwise it might start shaking. Also, I'd recommend synthetic oil (not blended) as it has a sophisticated twin turbo engine.
It is a beautifully designed car: truly very classy.
The cup holders are in a very awkard place though, you have to be a contortionist to get to them. This is really the only design fault I think.
I would like to add that the TT 225 is not in fact a "Twin Turbo" system, but is in fact a 1.8L Inline 4, with a single K04 Turbo charger instead of the smaller, less efficient K03 Turbo on 180 hp 1.8T's, Dual Side mount intercoolers, and stronger rods... this car much like the K03 1.8T's can benefit greatly from a chip which can add up to 40hp and almost 100 torque!