tl;dr : Most admire him, but I'm a cold-blooded strategic mind, not a sentimental idiot.
Most do admire him, but taking a closer look, well... sorry for my poor vocabulary... he gave us ILLUSION of hope, freedom, an as illusive was that... goddammit, I lack words in english. Herzogtum Warschau. Completely artificial, in terms of politics, entity without any serious influence, without a chance to stand against the tides of Napoleonic Wars. Actually, it looks to me, that he only create that "entity" to give Polish soldiers hope for freedom, to manipulate them to serve as his puppets. It took some territory, and as far as I remember, was burdened with supporting french troops, stationed on it's territory. So Napoleon earned ally with territory, who had absolutely nothing against serving under his commands, both with fodder, land, supplies, therefore - strategic assets, it had no threatening power itself.\
That's as far as I remember from what I learned like, 3 years ago?
Now is the middle of the night, in the middle of pre-exams period, so I might not be a reliable source.