Within the popular history of Napoleon, he is nothing but exactly as you mention, a warmonger. He wages wars of conquest and acts only in the interest of glorifying himself.

However, was Napoleon exactly this? As usual, all humans are far more complex and deeper than they are presented. Napoleon was a fine commander, legendary for his skill in command and luck but was he a warmonger? I have approached this in a previous bad history post which does reference many tropes about Napoleon that are unfairly presented upon him.

Did he create a situation that was unfair to the defeated? Yes, but how many times did he declare war? Only twice of a series of wars directed at the defeat of Napoleon. Did he force the nations to declare war? Was he pushing for war? Hardly, he himself wanted peace in the last years of his reign and reluctantly declared war on Russia since they broke and turned their back on France of which only Spain is the only sin to describe Napoleon as a warmonger.

One of the reasons Napoleon's legacy is contested is that, despite his military actions, he was also a lawmaker; the Code Civil that he had a large hand in writing is still the basis for French law, and was exported through his military conquests to many parts of Europe. He was seen at the time as bringing stability to France after the chaos of the Revolution and the political swerves and u-turns of the Directory, and he managed to pull the teeth of the most violent forces of both Jacobinism and Counter-Revolution. He allowed émigré nobles to return to France, healed (somewhat) France's rift with the Catholic Church, and removed the threat of massive banditry in the west of France by dissolving the Chouan movement.

He reformed many states, particularly France and western German ones, from 'Feudalism' (or, in France's case, Revolutionary ambiguity) to modern-ish bureaucratic states. He was the catalyst for the long process of unification both in Italy and Germany, and abolished the Holy Roman Empire, seen by many contemporary progressives as an anachronistic and backwards institution. He instituted the lycée, which is still a major part of French education. He also emancipated the Jews of his conquered territories (and Jews had full civil rights in the Napoleonic state, which was practically unique at the time) and allowed Poland a sort of state, which it had not had since partition in the 1790s and would not have again until the 1920s.

However, he also instituted a state with very limited political freedoms: no freedom of the press, not much freedom of political expression, a pseudo-secret-police under Fouché, a democracy that answered to the whims of Napoleon, rather than the electors (who he himself nominated in any case). He was an absolute monarch, and in real terms exercised far more power than Louis XVI ever did. He 'rehierarchised' French society after the Revolution's aggressive egalitarianism and even instituted a new nobility. He changed the character of many of the things he seemingly brought back, such as the nobility being defined by public service rather than being a form of inherited property, but he still reinstituted them. He drained France's population through years of successive conscription, and his occupation of Spain and Portugal was notably brutal for the time.

Sudhir Hazareesingh also argues that, during his temporary return to France in the Hundred days, he became an easy way for Republicans and other radicals to oppose the restored Bourbon monarchy. Even though those radicals had opposed Napoleon himself during the First Empire, he became identified with resistance and opposition to the Monarchy (which eventually helped his nephew to gain the presidency of the Second Republic in 1848). This is, however, a point specific to France.

Some good reading on the Napoleonic state and Napoleon's non-military actions are Geoffrey Ellis's The Napoleonic Empire, Clive Emsley's Napoleon: Conquest, Reform and Reorganisation, and Martyn Lyons' Napoleon Bonaparte and the Legacy of the French Revolution.

Ultimately, where you stand on Napoleon depends on your own context; British sources have tended to see him as a conqueror and warmonger, because that his how he imposed himself on the British consciousness. French writers see him alternately as a military leader and as a reformer, although the former has a positive tint for many, since French military power and influence reached its apogee under Napoleon.

Do you place a greater emphasis on military actions or civil reform? Do you think his reforms justify his authoritarian Empire? Was he justified in taking absolute power given how chaotic the Revolution was? How seriously do you take his seeming liberalisation during the Hundred Days - was it a ruse to get liberals and Radicals on side, or was it genuine?

These questions don't have easy answers, and they all affect how people see Napoleon, and hence his reputation.