As for me, it's obvious why I'd watch this documentary--I love beer (and make it myself) and I love to travel. However, I could see non-drinkers having far less interest in this film...non-drinkers and xenophobes!
Frank McCourt (the author of the book "Angela's Ashes") narrates this documentary. He's an interesting guy to narrate, as he's kind of Irish and kind of an American. His family is Irish and he lived in Ireland for some time--but he was born and died in the States and lived here for many decades. I was surprised, then, with his Irish accent as he really was at least as much an American than Irishman. Perhaps to someone from Ireland he doesn't sound so Irish and they think he sounds very American!
This film is less a set of 'must-see' pubs if you visit Dublin. Instead, it is intended to give you the feel of a good Irish pub--the look, the style, the way they pour a proper pint and the city itself--such as its famous writers, the Book of Kels and more. In other words, it looks more like a film intended to infuse the viewer with a desire to visit the city and drink all this in--the total Dublin experience. And, if you are planning a visit, it seems like a must-see film. Or, if like me, you one day want to see the city, it certainly whets the appetite. Well done and worth seeing.
By the way, although I have not yet been to Ireland, you would get the impression watching this show that Guinness is the only stout in this country. I actually prefer some of the other brands which are made there as well such as Murphy's and Beamish. Give 'em a try as well as a Guinness!