Really nice car and for the most part they do not have too many problems. You really should have it inspected by an Audi shop in your area just to be safe.
Things to check:
Check underneath w/ belly pan removed for oil leaks
Inspect Serp. belt (do not last long on this engine)
Check battery, make sure charging system is working
VAG Com full scan or at least check Engine DTC's
Test drive and listen for any wheel bearing/tire noise
Inspect front suspension for worn ball joints/bushings/end links
Check the aux. radiators for coolant leaks
You really want to listen to this engine during a cold start up and make sure there is not excessive noise from cam adjusters/timing chains. A small amount is normal but if it lasts for more than a second than I would stay away.