Marc,
By the time of Waterloo Napoleon was in decline - he did still take the Allies by surprise though. His return to France had been one of his gambles and I doubt he had really considered all the potential problems, military, political and diplomatic.
He has to be given credit for organisational talent at the beginning - he could not have succeeded without it. Later on he got over-confident -the Russian campaign being the finest example. The re-organisation of the army for the 1813 campaign was quite impressive but it was quantity not quality,
regards,
Susan