My 20-something son talked me into seeing it with him recently. It was interesting. The only part that I felt was really over the top was the polar bear scene. Before I watched the movie I felt that there is data suggesting that global warming could be a real phenomenon, but that it hasn't yet been proven that it is a terrible crisis and that proponents are making predictions that have not been supported scientifically. That is the same way I felt after the movie.
The central points made by Gore in the film centered on a graph showing the temperature and CO2 for the last 650,000 years. The fact that these two variables have risen and fallen together over this whole period is very suggestive, but as I recall the film does not answer the question of whether it has been shown that the temperature depends on the CO2 and not the other way around.
Also Gore makes a big point to show how much higher the CO2 is now than it has been at any time over the last 650,000 years. This is true but after watching the film I wondered if Gore had not exaggerated the amount of increase somewhat by not having the bottom of the graph correspond to zero CO2. I would have to see this part of the film again check if he did this.
Basically I would have no problem with older students watching the film as long as there was some classroom discussion of how the data might be interpreted in other ways. There is nothing wrong with provoking thought and discussion. I would be concerned about younger students being shown the film, or if it was not presented with discussion of alternative interpretations and the reasons why some people are skeptical.
To my thinking it would obviously be wrong to somehow prevent young people from seeing the graph presently by Gore as I don't think the actual measurements are in question. Of course the graph could be presented without the movie.
One thing I did like about the movie was that the graphics were presented in an attractive way that might get young people more interested in a discussion of scientific data.