First off, this is unauthorised product, which means that the members of Pink Floyd do not participate. Generally, you want to look out for this sort of thing, as there is next to no music and it's largely no-name talking heads sharing their opinions. With most of these critical reviews, you're better off discussing this with your mates or better yet, picking up a book.
However, this entry does contain some music, and at least some comments from David Gilmour. The production values are high for this kind of project, and the analysis of Atom Heart Mother runs far longer than the album itself. Most of the footage interviews the composer Ron Geesin, and there's a lot of technical talk about the arrangement of the music. You won't see much in the way of performance footage, just a clip or two here and there. You have to really love Atom Heart Mother to find this analysis compelling.
All of these "critical reviews" should be approached with a wary eye. As the film makers do not have the rights to the music they can only use small tidbits, so if you're looking for real concert footage or interviews with band members, you'll be sorely disappointed. This is one is a bit better than most, but caveat emptor most emphatically applies.