Piece of work
The most famous instance of this phrase is Shakespeare Hamlet Act II, Scene II, “What a piece of work is a man! How noble in reason! How infinite in faculty!” These days, to describe someone, as ‘a piece of work’ can be negative or positive, depending on the context. This latter usage is American from the 1970s. In Britain, by usually adding the word ‘nasty” we get nasty piece of work, which has been a popular description for an unpleasant person since the 18th century.