Overall Reliability has gone up in my experience... but the 'quality' has gone down.

Little things like:
Interior paint flaking off.
Rust showing up on the exterior trim (dealer response.. 'known problem')
Interior rattles getting worse with age.
(sunroof exploding for no reason 😃)

I've put over 150k miles on each car... each generation got a little bit worse.

I have no doubt the A4 I just handed down to my kid will last another 80k miles. It just won't be as solid or look as nice as my first B6 did at that same age.