In the ideal world of Alfas, I want to see service stamps in the book from a good independent (or possibly well-respected dealer), as well as receipts for all parts and work done.
That way I know that the car has been looked at regularly by someone who knows what they're doing, as well as any work having been done by a competent person.
I want that in my owner's book when I sell a car, to prove to a buyer that the car has been loved - and I want to see proof of that when I'm considering buying a car off someone else.
I seldom do any work on my car myself these days, save for the odd inter-service oil change. I'd rather a good mechanic get my car up on a ramp so he can see properly underneath for any problems - or just as importantly - potential problems, as well as having all the correct diagnostic gear that even a 'talented amateur' wouldn't have.