Usually NDAs cover much more specific information than what he writes about here. They basically cover the company's intellectual property - the specific technical information that lets them do their job better than others.
Stories, anecdotes, and cultural observations don't fall under this, unless those stories reveal the existence of projects/technologies that the company wants to keep secret. You can say "here's why I think my past employer was dysfunctional", and it won't win you any friends, but they can't come after you legally for that.
The only thing here that looks like it may've been confidential at some point is the existence of ClearType or the tablet PC. But since both of those were launched - albeit late - they're public information anyway, and he's not telling you anything you couldn't read in the tech press.
