I would add

3) These four games were both genuinely worth watching for any soccer fan with different dynamics but huge suspens. I know 80% of the club participants have been more or less the same in the last decade but I like this and again I feel why the superleague is a natural (I know some will disagree)

4) The mental and history aspect: FC Bayern players that did not want to be the first one to lose against these "Arsenal babies", the Barca players and coach that want to teach Luis Enrique a lesson, the grinta of Atletico