Starts out strong investigating the myths and origins of themes that will ultimately end up in Alien but then slowly descends in to the usual trope of talking heads telling you nothing new, with the notable exception of Dan O'Bannons wife who does cast some light on the writer, his life and his work.
However, the documentaries biggest failings come in the second half when it lifts interviews wholesale from the three hour documentary found on the Alien Boxset DVD. These interviews are then composited into still frames of the Nostromos console which gives the whole documentary a sense of being a YouTube click bait film trying to avoid content ID and leaves you with a feeling that perhaps you should be watching the much more exhaustive and well made documentary sitting in your DVD collection.
Finally after hand waving away the majority of the films genesis and production in a matter of minutes, the documentary examines in detail the chestburster scene. A scene so iconic that it feels like there is very little new to say about it after 40 years of analysis. Something which is borne out when you watch 45 mins of random talking heads telling you shocking "new" revelations such as the scene is a metaphor for fear of childbirth. While others try to noodle over the fact that Veronica Cartwright got a face full of blood and fell over during the filming which was kept in the film (Something Cartwright herself confirms in the documentary)
For newcomers this documentary will not give you any understanding as to the phenomenon within pop culture and horror that Alien is. While for hard core fans of the film and the series, there is a lack of anything particularly new or interesting to learn unless you like listening to random people say the same old things while sitting against a black backdrop.
Personally, I would recommend saving the price of a ticket, watching the three hour documentary available on the DVD and BluRay box sets and spending the money on the JW Rinzler book Making of Alien that was released recently.