The writeup by Peter Sanderson takes a look at the history of X-men, which was created in 1963. Considering the amount of history X-men has, it's not inaccurate to say that the writeup in the book is rather brief. It does go through the main gist and takes a look at the main characters. There are stories like how the characters are created, the differences between the comics and the movies, for example Mystique is Nightcrawler's mom in the comics but not the movie.
There's a good amount of art in the book. Unfortunately, there's also a good amount of film stills. Good thing is all are captioned and informative.
That's all. Just history and art. There's no production stories, not much anyway, of how they shot the movie on ground.
If you're intending to get the book, the paperback version is more worth it for the price.
There are more pictures of the book on my blog. Just visit my Amazon profile for the link.