I can only speak from my own interest but it seems the early S40's were 'better' in some respects. I think maybe Ford's penny-pinching took some time to fully roll out to these models and certainly the early S40/V50's didn't suffer wheel bearing failures and the a/c condensers were better than the 2007+ cars.
Not sure on interior build quality but ALL manufacturers seem to have compromised on interior quality, I believe this to be some European thing about restricting the use of oil-based products like Plastic and Rubber, or at least using a Plastic that's more eco-friendly....you know, with once-only fixings
Paint quality is another issue with new cars with oil based paints being replaced with other types there's definitely a reduction in paint finish quality.
That said it normally doesn't take long for innovation to catch up and even make better what we had in the past.