Wow. Shoot 'Em Up is exactly what it claims to be. An action movie. Balls to the wall, no holds barred, but nothing more. And that's exactly what you get. Don't go expecting high art...SEU doesn't take itself seriously enough for that. But that's exactly what makes it work. It KNOWS it's over the top, and doesn't try to hide it. Clive Owen's Smith character is the Bugs Bunny to Paul Giamatti's Hurtz Elmer Fudd. The film takes the best cartoon elements, makes them flesh, and still kicks in that over the top craziness. Bad puns that are so bad they're good, action sequences that there just for the sake of having an action sequence, and the wildest sex scene ever...it's amazing. It's the funniest, coolest, most amazing mix of stunts, bad one liners and paper think plot lines.
You get everything you expect from Shoot 'Em Up...and it's all great.