Arnold 5 brought a host of new features and additions, including a new aiStandard Surface shader that relates the old material of earlier versions of Arnold. This move sets up Arnold to make changes to the renderer without having to introduce new shaders every time.
Some things have changed with the new AiStandard Surface material’s attributes, so it does take a bit to get used to what does what. Lighting TD Arvid Schneider has covered creating various materials in his Arnold Render series, this time creating a chocolate shader, using Arnold’s Standard Surface.
Watch Arvid throw together some utility nodes along with the new Standard material to create a nice chocolate shader that you can add to your shader library.