The Empire style? It is a style better showing in furniture, and not so much in painting, sculpture or architecture; basically it is the interior design popular back in the days of Napoleon; to simplify it even further, it is how Napoleon decorated his house, and how everyone else did it for as long as he stayed in power, or rather, for as long as he stayed alive. This is why if you want to see the Empire style at its purest, go to Rueil Malmaison, the place where he decorated himself. Josephine helped.
So, how would I describe this style, if I were completely ignorant of its historical context? A paradox! The Empire is a paradox: it is rooted in Neoclassical austerity and reaches toward the most garish Oriental opulence. It is the interior design that makes you think of an exterior, so much it depends on rectilinear forms typical of architecture; and for the history buffs — pure kitsch, pure Napoleon; a chandelier falling from the ceiling inside the great mind, lighting its darkest recesses.