I hesitated to watch this movie at first due to its awful name.
However, I have to admit, apart from the cheesy acting and dialogue that could have benefited from a second and third draft, Flight 666.... was actually pretty entertaining! It's one of those "so stupid it's fun" kinda movies.
The premise of a haunted plane sounds silly - and IS silly - but, if you just go with it, the plot does keep you watching till the very end.
The movie isn't scary per se, but the original idea and nice twist makes Flight 666 a surprisingly competent film. It won't be winning any horror movie awards anytime soon - but it's fun for a one-time watch.
I'd rate this... 2.75 popcorns out of 5. Decent, fun, intriguing, and definitely not the worst film I've ever seen.