As many others mentioned it before, it is just awesome. Very good acting mixed with exciting Drama in a very cynic way of fun! I just love it, exspecially the scene when Skylar presents Walter the big pile of money they made!! Just standing there and everyone knew what they were thinking.. just the best.
The one flaw I recognized was given in a prior comment: The germans in the beginning of the 5th season are not speaking german correctly, it is for a german understandable, but not good at all... that is a problem in many tv shows, I dont know about other languages... but doesnt USA have german actors to play such minor roles... like Sandra Bullock, she can speak it quite well^^