Maintenance isn't too bad, I mean yes, a lot of things need a few extra steps compared to other cars...but there are plenty of forums with step by step DIY instructions on how to do everything.
Basically a good rule of thumb is that a Toyota/Honda will cost you $500/yr to keep running. And an Audi will cost you $1,000/yr.
Reliability wise, the mechanical bits are pretty reliable. They had a major issue with the coilpacks, but they did a recall on those, and the new ones are supposed to be bulletproof. The electrical bits on the other hand have their fair share of gremlins...but those are an annoyance, not anything serious + Audi has an onboard computer that catches these things...so you'll know when your turn signal burns out.