As others have indicated, the Correspondance is the best place for what Napoleon's views (including such things as his thoughts on the campaigns of Julius Caesar, etc.). There is a very fine new and more comprehensive edition published over the past several years by the Foundation Napoléon (though it lacks some material actually signed out by Berthier that is in the original edition published under Napoleon III). Of course, one has to evaluate each letter or instruction in its own terms: addresse(s), time, intention, etc. to come to one's own conclusions.
And there are a host of memoirs by people who were close to N for many years: Meneval, Fain, Gourgard, Bertrand, Las Cases, etc., etc. etc. Again, you will have to evaluate each of these on its own merits considering the authors, time, etc.