Not much, to be honest.
We knew that big nations always win,
that reigning champions don't usually do well on the next one,
that beating Germany is the one thing that every team aspires to - those who aren't in actual contention for the Cup,
that possession isn't the key to the game,
and neither is the number of completed passes,
the passing accuracy, however, very well might...
that England isn't good at all, never mind the 4th place,
that the host nation typically is given a leeway, even to dope themselves to retardation - even the manager for some freaking reason...
that runners up are always forgotten, small nations including - anyone remembers: Czechoslovakia twice, Hungary twice, Sweden? now Croatia...
that a good dive or a handball might secure your team the World Cup, and therefore it's definitely worth trying,
that assigning a referee who never officiated a final before is the best way to ensure the big nation wins,
that a good manager is a decisive matter, while not having a manager at all (Spain) is not at all a good idea,
that leaving out a whole bunch of star players if you have 45 of them available may indeed be a good move - due to simple mathematics if nothing else (France), but leaving out just one guy might prove quite disastrous under different circumstances (Belgium),
and, last but not least, that you have to invent new tactics, a new kind of play to win the World Cup: there was Ginga, Catenaccio, German Machine, then Total Football, then Tiki-taka...
the French too invented a new one this time around, it is a new style alright - I just don't know what it's called - what you call it when you don't play a lot or at all but score a whole lot anyway?