I decided to purchase this film because I am a fan of Director George Lucas' other work, primarily the Star Wars saga.
I had little knowledge of the film itself prior to watching it, apart from the troubled 'making of' backstory that I read in a number of books about the years before Star Wars.
Unfortunately at the time of the theatrical release back in 1971 it appeared that Warner Bros just didn't know how to effectively market the film, thus leading to rather underwhelming ticket sales.
In later years the film would become somewhat of a cult classic, perhaps driven by George Lucas' later achievements.
For my part I was pleasantly surprised by this film. It is extremely well directed, the actors carry their respective roles with solid performances all round, and, perhaps most surprising of all, the special effects and locations appear to have stood the test of time rather well.
Another reviewer alluded to a re-release with added scenes and effects. I believe after the success of American Graffiti and Star Wars, Warner Bros re-released a theatrical version in the late 70's and included around 5 minutes of previously deleted scenes that George Lucas wanted in the original release. I would say this version available of iTunes is the later re-release based on the quality of visual effects.
If you are a fan of Science Fiction I would certainly recommend this film to you. The rather 'out of this world' dialogue takes some getting used to but the film as a whole will I'm sure keep you entertained throughout the entire 90 minutes.
Enjoy this piece of cinematic history.