His empire was a meritocracy and this drove unfettered fear into the conventional European power bases, whose leaders most commonly had anything but merit.
I would say he's not only a great man, but one of the greatest men the world has ever known. He benefited from war, but never sought it; in fact he avoided it in ever instance until he was left with no other choice. He only benefited because his enemies were less competent, an unfortunate side effect of status by birth.
The peaceful and relatively united Europe we have today was his dream, 200 years ago. His defeat let Europe lag as aristocracies blundered their way through politics, horrible pointless war, and continued legislation directed towards maintaining the stagnant status quo. One might even be able to claim that the terrible wars of the 20th century would never had occurred if Britain stood by her agreements with France instead of continually seeking conflict, not with Napoleon, but rather with an ideology of merit that threatened their social mediocrity.
Some might cite the invasion of Russia as an example of Napoleon's aggression, but he sought to avoid this at all costs.
There have to be a hundred messages written by Napoleon regarding his desires for peace with Russia, and his admiration and respect for Alexander. He knew he was being manipulated by both the British and his own government. Had Napoleon wished Russia harm, there were a dozen instances where he could have completely destroyed the Russian army, but instead, believing Alexander would be agreeable to terms of peace, wished to avoid further bloodshed. As in 1806 with the Austrians, after Borodino Napoleon allowed the Russians to remove themselves although total annihilation of their army was within his grasp.
Addressing his troops in 1812:
Soldiers: The second war of Poland has commenced. The first war terminated at Friedland and Tilsit. At Tilsit, Russia swore eternal alliance with France, and war with England. She has openly violated her oath, and refuses to offer any explanation of her strange conduct till the French Eagle shall have passed the Rhine, and, consequently, shall have left her allies at her discretion. Russia is impelled onward by fatality. Her destiny is about to be accomplished. Does she believe that we have degenerated? that we are no longer the soldiers of Austerlitz? She has placed us between dishonor and war. The choice cannot for an instant be doubtful. Let us march forward, then, and crossing the Niemen, carry the war into her territories. The second war of Poland will be to the French army as glorious as the first. But our next peace must carry with it its own guarantee, and put an end to that arrogant influence which, for the last fifty years, Russia has exercised over the affairs of Europe.
Russia forced Napoleon's hand, although Napoleon very much did not wish to move against her.
I wage war against your Majesty without animosity; a note from you before or after the last battle would have stopped my march, and I should even have liked to have sacrificed the advantage of entering Moscow. If your Majesty retains some remains of your former sentiments, you will take this letter in good part. At all events, you will thank me for giving you an account of what is passing at Moscow 
Napoleon was a reformer, a lawgiver, and his wars were defensive in nature. He inherited war upon assumption as head of state in France in 1799. 1805 was an invasion of an ally by Austria. In 1806 Prussia chose war, not France. Russia was soundly defeated in 1805 and 1807, allying itself with first Austria then Prussia. Godoy in Spain wrote to the Prussians that he would attack France if the Prussians won. Napoleon found the correspondence and that was one reason for the invasion of Spain. For the invasion of Portugal, Spain participated with France. 1809 was Austrian aggression again. Russia can be classed as a preemptive strike as Alexander chose to go to war over Poland and other issues as early as 1810. 1813 and 1814 were a continuation of the 1812 war and in 1815 the allies chose war, not Napoleon .
Also consider his social reforms. The Code Napoleon (still contributing to constitutions in many nations today), the deconstruction of feudal systems, replacing them with meritocracies, rights for women, equal taxation, social systems for the poor, secularization of the nation, the development of universities and education regardless of wealth. In 1807 he wrote:
Of all our institutions public education is the most important. Everything depends on it, the present and the future. It is essential that the morals and political ideas of the generation which is now growing up should no longer be dependent upon the news of the day or the circumstances of the moment. Above all we must secure unity: we must be able to cast a whole generation in the same mould .
He emancipated the Jews in every area he found himself in control (which is why comparisons to Hitler are so absurd), and while some may criticize his taking the throne, he was the only legitimate ruler in Europe, having being elected to that position as Emperor of the French (not "of France").
The impact Napoleon had on the world was without a doubt one for the better. His life really is a tragedy, had Britain not continually financed and sought war, Europe would have been given a 200 year head start. He never sought war, but certainly never backed down. Those regions that fell under his control were liberated from the yokes of totalitarianism and through the Code Napoleon granted liberties not experienced in Europe again until the tail end of the industrial revolution.
I would strongly recommend everyone who is interested in this period listen to the Napoleon 101 podcast. It's done by Dr. David Markham, a distinguished Napoleonic historian and head of the International Napoleon Society.