Leonardo DiCaprio as Jay Gatsby, and Tobey Maguire as Nick Carraway.
I recently read the book and enjoyed the themes and symbolism. I understand what they're going for, but the trailer seems a little too flashy for a 20's setting, but I'm no expert on the Jazz age myself, so what do I know.
Also, here's an article about how the 3D is suppose to change movies:
Not sure if I'm buying into that. I've heard these claims about previous films and wasn't impressed.