Napoleon basically had absolute power. The Senate was more of a governing body that was created simply to have a place for legislative advisory. In almost every aspect of government, he could dismiss and replace people at will, act on anything he saw needed to be done, and even meddled in the affairs of towns.

For lack of a better word, Napoleon was an Absolute Monarch but the real difference is how he acted. He was meritocratic and supported trade, he acted to protect the middle class (with the exception of the Continental System, which was an attempt at economic war that hurt the middle class).

Absolute monarchical power, as has already been said. Despite imposing the Code Civil, he didn't think himself bound by it any more than the earlier Bourbons thought themselves bound by French Law, apart from the Fundamental Law of Succession, of course! His betrayal of the Revolution, and indeed of his own expressed radical Republican principles, was one of the reasons why French Republicans loathed him and his dynastic successor; of course, Nationalist sentiment and mythology won in the end, such that he became a hero of the Republicans as well as the Orleanists. The consitution of the Empire was designed purely for consultation and for rubber stamping the decrees and edicts with which he ruled his Empire.