Jack's commentary is great
There are threads here parsing Nicholson's commentary, some of the posts made BEFORE the writer had finished actually listening to the entire commentary, apparently.
Yet no one seems to have mentioned: the commentary track is one of the best ever for any movie.
Why? Partly for what it is, and partly for what it isn't.
What it is: It is a warm remembrance of the events and circumstances surrounding the production by a major star/character in the movie. It's one of Antonioni's most accessible movies, so Jack isn't hobbled by trying to explain it. It's a paced movie (not saying it's fast, but steady). Antonioni was a master of the long shot, and this movie is a beautiful example. So Jack's relaxed conversational tone is perfectly suited. It's fun to hear his memories - however wrong some of them might ultimately be.
What it isn't: It isn't buried in minutiae the way some scholarly commentaries are, nor is it a super-nerd conversation by two super nerds talking about the movie business and the filmography of the caterer on the production and other silly uninteresting drivel (try to listen to the "Mark of the Vampire" commentary... jesus shuddup!). It isn't filled with English major interpretation of every scene, and isn't a discussion between Jack and somebody else about what actually happened.
Jack sits comfortably for the length of the movie and talks about it. This wouldn't work for every movie, but it works for this one, and makes the Commentary track one of the very best I've heard.