Too bad you didn't dig this. I went absolutely bonkers for it when I saw it in the theater without having any preconceived notions of what to expect. I'm not sure Campbell Scott is completely to blame for his performance, it's not easy to speak that staccato, stylized Mamet dialogue. But he is pretty emotionless, you're right.
For me, the whole movie is such an amazing and complex puzzle, and right up to the end you really never know what's coming next. This led me to watch every Mamet movie available (as well as reading some of his plays). The other ones worth mentioning: HOUSE OF GAMES, THE WINSLOW BOY, and the recent SPARTAN.