Anyone with a remotely newer Audi probably won't have horrible things to say, is there maintenance required with older or higher mileage cars? Yep. Is the maintenance better left to Audi mechanics (doesn't have to be dealer)? Yep.
They don't. The 3.0TFSI is a pretty damn reliable powertrain as far as german cars go. I've had mine 5 years and zero powertrain issues whatsoever. Not even a check engine light.