He was a megalomaniac as well as a narcisist egomaniac in the same way of Cæsar, Alexander, Hitler, Stalin and even Churchill. But Napoléon's legacy is very, very different from Hitler's. Napoléon left behind a justice code that is still applied in liberalist countries and a huge cultural saga in France and Europe. How many people think Napoléon is a monster and how many people think he was a genious and the greatest Frenchman ever born? How many people think Hitler is a monster and how many people think he was a genious and the greatest German ever born?
To make things even worse I think you should think it this way: What if Hitler was French ruling France in the 1930-40´s...
I'm out of ideas now, but this would be a fun thread for What-If: what if Adolf Hitler were called Adolphe Hitlère?
Indeed, the idea was originally that what if France had someone like Hitler instead of Germany...or if both had such strong politicians?
Fortunately for the campaign, France's new president is a very strong figure with large popular back-up. His name's is Friedrich d'Épéhéry Bonaparte.