Matt Barry over at The Art and Culture Of Movies has recently posted an insightful short review of Orson Welles's Touch Of Evil. He calls it an unnerving film, which it certainly is, but points out that one of its most unnerving aspects is the way Welles goofs on our expectations of what a gritty little film noir should be.
The film's extreme stylization both seduces us into its nightmare world and distances us from it as an aesthetic creation, all at the same time. Touch Of Evil was not quite the last classic noir — I think you'd have to give that distinction to Odds Against Tomorrow, which came out a bit later — but its self-consciousness about the form was a sure signal that the tradition had all but played itself out. One definition of a neo-noir is that it's at least as concerned with commenting on the form as with working inside it. In some ways, Touch Of Evil was the first of the neo-noirs.