Blundering to Glory: Napoleon's Military Campaigns (Owen Connelly, 1987) is a concise but rich history of Napoleon as a commander. Connelly portrays Napoleon as a master improviser--a "scrambler"--whose genius was an ability to adjust on the fly when battles didn't go according to his original plan (which they almost never did).
Connelly contends in his conclusion that Napoleon was the greatest commander of all time, but as much as I enjoyed and learned from this book, I'm still not convinced that he was even the best commander born in 1769. (As I'm sure will surprise none of the ten people who read my blog, I'm a bit of a Wellington partisan.) I think what kept Napoleon on top so long was that no other country had subordinate generals who could compare to the marshals of the Empire. I swear half his great victories would've been defeats without Davout, or Massena, or Murat. And when you look at the diverse background of the marshals, it just goes to show how much everyone but France was limiting themselves by only allowing aristocrats to command. I mean, England was damn lucky that the military genius that was Wellington happened to be born in the body of a younger son of an earl. If his father had been a shopkeeper (like Massena's) or an innkeeper (like Murat's) he would've been lucky to be more than a sergeant in the British army.
But I digress. If you're looking for a good summary of Napoleon's generalship that's neither too technical nor too simplistic, this is an excellent choice.