This particular book is interesting for the 50 films that Crowther singles out as the greatest. My friend and I both agreed that, while there would probably be some changes to the list if it were written today, overall these selections still hold up well. It's also an interesting reflection of some films and filmmakers were highly regarded at the time but have since largely vanished from the critical consciousness (such as Flaherty). With all the debate over a "canon" in film studies, Crowther's book is still a good starting point for novice film buffs to begin exploring further on their own.
Incidentally, I did make it a point to see all 50 films in the book -- some of which I only caught up with in the past few years, such as Clement's FORBIDDEN GAMES.