I've seen 82 of the films on that list and like Ric, I have minor quibbles with the placings.
Mind you, of that 82, I'd have to add that at least half of them were pretty average, in my opinion
A quick check of my dvd shelves shows 28 of those titles present with another 24 that didn't make the list.
Sci-fi films are a strange and subjective genre indeed. What will make one fan slaver at the mouth with enjoyment will induce a trance like state of utter boredom in another. But hey, I'm a sci-fi junkie, so bring 'em on, brother!