During the Egypt campaign Napoleon laid siege to Jaffa, and after the surrender allowed his troops to engage in two days of rape and slaughter. Ottoman and Albanian prisoners who had previously agreed to surrender on the condition that they be allowed to leave, were instead taken to the beach and bayoneted to death. Now, before all this the messengers Napoleon had sent to speak with the defenders had been castrated, murdered and had their decapitated heads displayed above the walls, so we can't say it was entirely without provocation, but anyone looking to oppose Napoleon would have a field day with it.

Not too long after at the Siege of Acre Napoleon was forced to leave and place command in the hands of General Jean-Baptiste Kleber, an opponent of his. Before he left though, he ordered his artillery (which he couldn't take with him) to fire off their remaining ammunition... into the town. Kleber was left in no position to take the castle after Napoleon's army left and also in no position to leave himself, as Napoleon had decided to take all the ships with him.

In the Spanish and Russian campaigns executions were rife, with Spaniards suspected of having ties to anti-French groups being common and those of Russians suspected of burning crops and buildings.

Napoleon's ambitions and his narcissistic attempt to recreate Alexander's conquests cost the lives of of anywhere from 3 to 7 million soldiers and civilians. Whilst not as driven in hatred as Hitler, he was certainly as ambitious.

reviled by many in the West

that quoted a English woman's diary

One quote from the diary of a woman who lived in the country which was the main enemy of Napoleons France is really not enough evidence to base an assumption of the opinion of "many in the West".

In fact I would think it was perfectly natural that a person living in the UK during the time of the Napoleonic Wars would not look favourably upon Napoleon.