Why does everyone think this movie is so great?

Rating: Null/10 (12 November 2011)

If there's one thing I can't stand it's plot holes, and Alien is full of them.
Here's is a few things I don't quite understand.
Why is the only weapons they have on board flame-throwers? Why are the crew members so stupid as to not realize staying together would be a lot safer? Each time one of them wonders off alone, which they do one by one, they become lunch for the dreaded space monster. You'd think anyone with sufficient training would understand the need for a 24hr quarantine under even life threatening circumstances. That stupid cat. Any time anyone goes near it it hisses and bolts away drawing whoever's following it towards the alien, was it working for the Alien? Why don't they have an escape pod or pods large enough to fit the entire crew? Is Lamberts only role to kick and scream and get in the way (very annoying clichÃ© character)?
They don't close the door after the alien detaches from Kane's face (not after there was enough time for the face sucker to possibly escape the enclosed area). And They don't chase the Alien that emerges from Kanes body until after it's long gone.
The acting was definitely solid but the characters actual actions not very believable at all. More than anything I found this movie to be incredibly annoying.