AUM + k03s FTW... oh hang on, didn't mine come with a K03s already bolted on...ahem...

As for the mk4 1.8T, they have quite a few minor electrical things that tend to go wrong, but are generally easily & cheaply fixed, plus they are all "known" problems and thus easy to find and rectify.
As for the engine itself, they are indeed bomb-proof, as long as they are looked after and serviced well then you shouldn't see any catastophic problems tbh.