It's been a while since I watched a real movie. It was sufficient for me to know that John Hamm was starring in a dark comedy for me to watch it with no further information. I do believe its best to just watch it with minimal prior awareness. Just like some excellent movies of yesteryears, this movie will grip you and stay with you even after the end credits roll.
Anybody with a creative bent and also work experience in a corporate environment will quickly warm up to the protagonist and identify with him. Creative people want the same things as others, but others fail to accept the manner in which creative people operate.
The movie is a critique on the culture of supremacy of mediocrity. It isn't that mediocre people are without their little fallacies and foibles, but somehow their issues are ignored. The odd behavior of a creative person, regardless of his or her contribution is however chastised.
If you've had enough years of life experience in the work force, then this movie will provide some catharsis. The protagonist experiences the same fears, pride, and injustices you have experienced and so you feel less alone.
I'd whole heartedly recommend this movie to folks with some professional life experience. If you've got a bit of creativity in you, you'll like this move even more.