I really enjoyed this film when I saw it at the Saturday matinée during its release, and remember that experience vividly, but watching it now nearly 40 years later, I can appreciate that it has not aged well at all. This was clearly re-packaged to capitalize on the mountain adventure movies of the time, and to that end it has some gorgeous photography, but the story-- and especially the ham-fisted narration-- are just too hackneyed to bear. Even if it's based on truth, which the film clearly asks you to question, especially with its grossly fake documentary stylings, I can't imagine kids today would enjoy its slow pacing, stiff acting, and real animals. If you want to study it as an artifact of truly typical fare for the '70s, it does have its curiosities-- and for that matter, you could look at the "Benji" films too. But there's a reason why the "Benji" films are not considered classics, which is that they were simply bad. So is this.
There are far better films from the era to enjoy, even for children.